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2000 Seville (STS) - LH cooling fan not running


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Hello all:

Great to be back! My 2000 STS has been running hot (in my *opinion*) and I have been reading the archives and performing some cursory checks. I'm stumped. My temp gauge (analog, pictured) has always ran at 12 noon regardless of outside temp or A/C, etc. This year I've noticed that it will get to the 1:00 bar, and usually up to the second to last bar before it starts to cool down a little. If I'm in traffic or a drive-thru the gauge creeps up every couple of minutes. I had one incident last month where it went between the last bar on the gauge and the red zone (got the ENGINE HOT A/C OFF message), and it cooled down after driving several minutes.

Here's the history and diagnostics I have performed so far:

1. Coolant changed at ~50K in spring 2009, 50/50 w/pellets

2. New radiator at ~70K (tank cracked) 12/22/2009, replaced 50/50 and pellets

3. Only "CURRENT" code is an RSS code, not finding any other codes indicating bad fan relays, CTS, etc.

4. Maxi-fuses for both fans are fine, not blown (at least to the naked eye)

5. Purge line (3/8" on top of tank) shows coolant flowing freely at idle (done last night)

The pictures I took are from tonight - specifically what the gauge readout was. The passenger-side fan WAS running, the driver's side was NOT running (non-running fan also pictured while car idled with A/C on, temp gauge as pictured). From what I read the HI kicks on in the high 230's or so. I'm wondering what your opinions are since my "running hot" opinion is not scientific (I do not have a specific coolant temp). I definitely notice that the gauge is reading higher this summer, though. Is there something wrong with my drivers' side fan?

In the interest of full disclosure, when my radiator was found to be cracked in 12/2009 (around 70K), the dealer also diagnosed me as having combustion byproducts in the surge tank. However, I brought the car in for an EXTERNAL leak so I disregarded their diagnosis and replaced the radiator myself with your help. She's been fine ever since, and I had the dealer put his money where his mouth was, in that he put (in writing) that he would split costs with me 50/50 if the head bolts pulled before 100K (she has ~94K now). FWIW, I am not losing any coolant anywhere, it does not smoke or smell like exhaust/gas in the surge tank, and it has never officially overheated (needle never went into the red).

I'm looking to trade her in, but for no other reason than my true love and pursuit for the last year has been a black 2006-08 DTS Performance. Until then, I want to make sure I'm doing my part to keep her maintained properly. Thanks for any help you can provide.

Mark

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As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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Hey Mark,

Good to see you back...sorry you are having troubles.

I don't think you will regret a newer DTS Performance Model...

That's what I have (a 2006) and I love it.

As to your cooling fans...

My understanding is that "BOTH" of them should run on low speed anytime the AC is on....

If it starts heating up... then they should "BOTH" kick into high...

Maybe the fan motor itself is bad.

If all the relays, wiring and fuses are good, I don't think the fan motor will set a code...

Someone will correct me if I am wrong.

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I agree with Jim,

Disconnect the wire from the LH cooling fan and hot wire it and see if it runs, if not replace it.

You say no codes so the relays are probably ok, check the fan connection and that the motor is good

Pre-1995 - DTC codes OBD1  >>

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Hey Mark,

Good to see you back...sorry you are having troubles.

I don't think you will regret a newer DTS Performance Model...

That's what I have (a 2006) and I love it.

As to your cooling fans...

My understanding is that "BOTH" of them should run on low speed anytime the AC is on....

If it starts heating up... then they should "BOTH" kick into high...

Maybe the fan motor itself is bad.

If all the relays, wiring and fuses are good, I don't think the fan motor will set a code...

Someone will correct me if I am wrong.

Thanks for your input fellas...I will see if the fan is in fact the culprit. I'll post back with the resolution (or further down the diagnostic tree if that's the case).

And Jim your DTS Performance is really sharp looking - I saw the pictures that were posted awhile back (the 0-60 test runs) - she looks sweet! I hope I'll get lucky and find one that I can get Majorguard on but if not it won't stop me.

Take care.

MM

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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Thanks for your input fellas...I will see if the fan is in fact the culprit. I'll post back with the resolution (or further down the diagnostic tree if that's the case).

And Jim your DTS Performance is really sharp looking - I saw the pictures that were posted awhile back (the 0-60 test runs) - she looks sweet! I hope I'll get lucky and find one that I can get Majorguard on but if not it won't stop me.

Take care.

MM

Thanks for the compliment...

Since then I had the grille painted to match the car color.

I think it looks better than the gray / silver looking, fake chrome. :) :)

My best 0-60 time has been 6.2 seconds...(bad wheelspin)

I ran it thru the 1/4 mile a few times, but it was VERY HOT and VERY HUMID that day and I only turned a 15.2. :(

I think it would do a 15 flat if it has been a little cooler and I didn't have such a problem with wheelspin coming off the line hard.

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I'm wondering what your opinions are since my "running hot" opinion is not scientific (I do not have a specific coolant temp).

looks like you're running about 240.

the dealer also diagnosed me as having combustion byproducts in the surge tank.

Why not borrow a block test kit from Autozone and run the test yourself?

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looks like you're running about 240.

Wow, thanks for that gauge! That's very nice to have as I never "really" knew how hot (or not) the temp was.

Why no borrow a block test kit from Autozone and run the test yourself?

I would if my intent was to keep the STS. I've been looking around the past several months and am pretty set on a DTS Perf. That decision is wholly separate from what may (or may not) be happening with the HGs. It hasn't lost a drop of coolant in 25K miles so I'm at peace with it.

UPDATE:

OK, I went out and hotwired the LH fan straight to 12V and it started running. I tested the pigtail going into the fan motor while it was disconnected (car running, A/C on) and it's not getting voltage. Hmm...any other suggestions before I start chasing down a wiring issue in the blue/black pair running into the fan?

Thanks again for everyone's help.

MM

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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I would swap in a known good relay, maybe the contacts are burned, the three relays are located below the fans

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

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I would swap in a known good relay, maybe the contacts are burned, the three relays are located below the fans

BBF, do you mean the mini relays pictured here for the fans, or are there more below too? I just swapped the ones with the arrows (#3604, labeled COOLFAN1 and COOLFAN2), no difference. The third one, labeled COOLFAN S/P is a different P/N - does this stand for Secondary/Primary? Might that be the cause? The contacts look good on all 3 FWIW.

Re-checked and still no codes. I also jiggled the wiring harness to LH fan while car was running, A/C on, to see if I could get it running (hoping for a loose connection within). Still no luck.

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<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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Cursory reading of the owner's manual shows me Serial/Parallel for COOLFAN S/P. Would temporarily unplugging the ECT help diagnose a "bad wiring" scenario?

If unplugging the sensor tells the PCM an overheat condition exists, would both fans not then come on? Therefore, if unplugging the ECT does not make both fans run, there is a wiring problem, otherwise there's something else afoul as both fans (in theory, anyway) would run? Am I making sense, or is it getting too late for me to think straight?

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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It looks like in 2000 its different than my 1996 was, in 96 there were 3 relays below the fans, in 2000 they are in the relay center (someone confirm that there was a change). Here is the schematic for the cooling fans for 2000, I hope its readable.

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MM, when you checked the pigtail did you just test between the 2 terminals? If so, also check with a DVM the black wire to ground - you should see no resistance as the black wire is the ground. Next check with the DVM from the blue wire to ground, you should read voltage with the car running and the A/C on. If you don't have a ground on the black wires terminal you have a wiring issue and could rig your own ground. If you don't have voltage on the blue wire, it is either a wiring issue or a problem with the S/P relay which is supplying the low speed or fan relay 1 which supplies the high speed.

If you look at the schmatic near the bottom it indicates the PCM will send a signal thru the dark blue wire to the S/P relay for a high speed fan condition, this energizes the S/P relay which in turn re-distributes the ground path for the RH fan (see the white wire coming off the RH Fan). This same signal energizes the fan relay 1 (high speed) on terminal E10 which then distributes the plus (+) voltage to the LH Fan thru terminal E11.

When BodybyFisher mentioned the contacts could be burned on the relays, he was not referring to the terminals you see when you remove the relay. He was referring to the contacts inside the relay which are not field servicable. There could also be a failure of the coils inside the relays

OldFart

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MM, when you checked the pigtail did you just test between the 2 terminals? If so, also check with a DVM the black wire to ground - you should see no resistance as the black wire is the ground. Next check with the DVM from the blue wire to ground, you should read voltage with the car running and the A/C on. If you don't have a ground on the black wires terminal you have a wiring issue and could rig your own ground. If you don't have voltage on the blue wire, it is either a wiring issue or a problem with the S/P relay which is supplying the low speed or fan relay 1 which supplies the high speed.

If you look at the schmatic near the bottom it indicates the PCM will send a signal thru the dark blue wire to the S/P relay for a high speed fan condition, this energizes the S/P relay which in turn re-distributes the ground path for the RH fan (see the white wire coming off the RH Fan). This same signal energizes the fan relay 1 (high speed) on terminal E10 which then distributes the plus (+) voltage to the LH Fan thru terminal E11.

When BodybyFisher mentioned the contacts could be burned on the relays, he was not referring to the terminals you see when you remove the relay. He was referring to the contacts inside the relay which are not field servicable. There could also be a failure of the coils inside the relays

Thanks for the diagram, BBF, and thank you for the additional input OF.

I tested the pigtail with a length of wire and a male terminal plugged into the blue side while the A/C was running. Tester was hooked to alternative, verified ground in the engine bay and no voltage was present in that wire. I need to replace my multimeter as I just have a test light, but the test light is functional when using the same ground and hitting the + post off the fuse box. I'll double check the ground in that pigtail by using the black fan wire as ground and 12V source as the battery post just to see if it's OK, if replacing the S/P relay doesn't fix it.

I'll get a replacement S/P relay on the way home tonight first, as quite frankly that will be easier than hunting down a potential wiring problem. If the new S/P relay isn't the culprit I will trace the fan power to see if there is any obstruction or obvious damage, along with double-checking that ground.

Based on the feedback everyone's given me I am pretty confident it's the relay/s or wiring to that fan. It sounds like the fanS (plural) are always on together when they're on, just a matter of HI or LO depending on the PCM signal being received.

Let me know if my "both fans" assumption is wrong...otherwise I will get back when I've tried those couple things. Thanks everyone.

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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I was reviewing the schematic when the PCM grounds the low speed relay, both fans run at LOW SPEED because the current is shared between both fans. If the LH fan is not working, the RH fan may not work in low speed either, what did you find

When the PCM calls for low speed cooling fans it grounds the low speed relay and that relay provides power to the RH motor. In low speed, the RH motor is grounded via the SP relay and the RH motor is grounded THROUGH the LH motor, causing the RH motor to share the current between both motors causing low speed.

When high speed is commanded, the SP relay directly grounds the RH motor giving it the full 12 volts, and the high speed relay is engaged by the PCM directly powering the LH motor giving it a full 12 volts.

This should be easy to figure out,

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I was reviewing the schematic when the PCM grounds the low speed relay, both fans run at LOW SPEED because the current is shared between both fans. If the LH fan is not working, the RH fan may not work in low speed either, what did you find

Finally had some time to take things apart a little today, and here's what I found:

1. Checked LH fan moter +12V wire (LT BLU) for voltage upstream (tested wire where it routes by the horns, close to underhood fuse bus). Car running, A/C running, RH fan confirmed as running at the time; no voltage to LH fan at that location.

2. Tested both 30A fan Maxi-fuses with them installed, car running, A/C on, RH fan confirmed running. +12V on *both* contacts on top of each fuse, so we're good there.

3. S/P relay replaced Friday, no effect on LH fan.

4. Removed #3604 fan relays and tested that voltage is getting to the relays when car is on and A/C running. Of course, voltage doesn't go to all 4 pins on each with them pulled out, but I verified that 2 pins on each relay (female end) are getting voltage at the same time.

I am going to get new relays just so I can validate that it's been done. I have switched their position which (to me anyway) proves that the relays work fine as the RH fan came on with either one installed.

Is there anything else I'm missing here? I've reviewed the schematic (thanks again BBF) and I think I have eliminated everything other than some sort of "issue" with the fuse block itself. Perhaps the wiring b/wn the relay(s) and the LT BLU outgoing wire? That's all I can think of, so please enlighten me if there's a flaw in my thinking.

Thanks again guys & gals.

Mark

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Hi Mark,

I think you have a wiring issue, not a relay issue.

The S/P relay is not energized during low speed operation, if you look at the side of the relay it has a small schematic printed that identifies the terminals, it will look the same as on the schematic BBF sent you. With a DVM or multimeter you should read 0 ohms between terminals 30 and 87A with the relay removed from the car. On the schematic BBF sent you they are the same as C10 and B11 at the top near the center. Unfortunately B11 is not identified, it is directly to the right of A11.

You really need an operating DVM or multimeter to expedite troubleshooting. If you take one lead of your DVM and probe the female recepticle for pin 87A of the S/P relay on the fuse block, and then take the other lead of the DVM and probe the blue wire at the plug for the fan you should read 0 ohms (or at least very close to 0). If you read nothing or very high resistence this confirms a wiring issue. Since you do not read voltage at the blue wire I suspect you will have an infinite reading, or the very least high resistance. If you read 0 ohms....I'm stumped.

Based on the assumption you have bad wiring, start at the fan and work your way back to the fuse block, or start at the fuse block and work your way to the fan. If you look at the schematic LH Fan motor you will see that the blue wire is pin number "B" on the plug for the fan, ultimately the blue wire is pin "E10" of connector "C1" going into the fuse block. Now look at RH fan motor on the bottom pin "A" the white wire goes up to the fuse block pin "D10", also on connector "C1". Based on the schematic both fans are in the same connector "C1" that plugs in the fuse block. Unfortunately I have no idea where connector "C1" is physically located on the Seville.

I hope this is of some help for you.

OldFart

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Hi Mark,

I think you have a wiring issue, not a relay issue.

<snip>

</snip>

I hope this is of some help for you.

Yes definitely, thanks for taking the time to relay all that. I got a decent multimeter and started at the fuse block. Honestly I didn't have as much time as I wanted and I had to start somewhere, so:

I read 12.54 volts at the #30 and #86 pin receptacles both fan relays at the fuse block with the car off, relays out. Turned the car on with A/C, and after I heard the A/C blower motor kick on, there was about a 3 second delay until the RH fan kicked on; I saw approx. 13.5V on #30 and #86 terminals on the working fan). The one difference I noted between the receptacles associated with each relay is that the LH fan's #86 pin read 13.5V, like the working fan's, *until* the fan is supposed to kick on (determined by the RH fan starting). With the multimeter on, it read 13.5, then dropped very quickly to 8, 4, 2, .19.

Long story short, the same pins are acting differently between the two. Any idea why the voltage drop on the one side? At this point I am thinking it's *something* wrong in the fuse box, and quite honestly I'm afraid to go in there (yeah, I know). I'll be straight, I am not very good at digesting the schematic and applying that knowledge to what's in front of me.

I've taken enough of everyone's time, and really appreciate the help. Please let me know if you know of anything that would possibly cause that drop, otherwise I'm going to perform more checks per instruction as I can and then take it somewhere if I feel like I'm getting in over my head. I hate that feeling...

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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You lost me, where are you getting pin #86, is that on my schematic? Talk in descriptions that adhear to that schematic I posted LH motor terminal "B" or "A", etc.... Am I missing something?

You should measure the resistance of each motor's primary wiring with the connector disconnected and see what you get. Maybe the motor is shorted internally.

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Pin 86 on all three relays is for the coil of the relay. To be clear, all three relays are for both fans. Cool fan 1 is the high speed relay and turns both fans to high speed during a very hot condition of the engine. Cool fan 2 is the low speed relay and supplies the low speed voltage to both fans for low speed operation. The Cool fan S/P relay is the series/parallel for both fans, it switches them from a series circuit during low speed operation to a parallel circuit during high speed.

The voltages you read on the coils were normal. I'm not sure which relay had the voltage slowly dropping because you identified it as the LH fan's. Tell me which relay, Cool fan1, cool fan 2, cool fan s/p and I may be able to explain the voltage drop. I doubt your problem is in the fuse block.

What is perplexing is the schematic shows both fans in series during low speed operation. In theory if you unplug the LH fan, the RH fan should stop running because it gets its ground through the LH fan. This also leads me to believe you have a wiring issue and I would suspect the blue wire for the LH fans is now grounded and that is why you do not read voltage on it. You really need to check for continuity as I indicated in post #17.

Based on your last post I'm going to assume you are not really familiar with reading schematics and checking for continuity. I don't say that to insult you. So I'll take a stab at describing how to do it. With your new multimeter turned on and set to the Ohms position for measuring resistance. Now take the two multimeter leads and touch them together, the meter should read 0 ohms which means no resistance. This means you have continuity. Now take an ordinary piece of wire, length is not real important, and strip both ends. Now take your multimeter leads and attach each on to each end of the wire you just stripped, the meter should read 0 ohms because you have continuity. (Please note if you hold the wires with your hands to the meter leads you will get a false reading) With the meter leads still attached cut the wire and watch the meter as it will go to an infinite position, this simulates an open circuit.

Now I want you to check continuity of the blue wire, engine off and key off. Remove relays cool fan 1 and cool fan S/P for the test. Unplug the LH fan. Take one of your meter leads, doesn't matter which one, and attach it to the terminal for the blue wire for the LH fan on the plug, not the fan itself. Take the other meter lead and attach it to a known good ground, what does the meter do? If it goes to 0 or a very low number that means you have a ground on the blue wire and you should not. If it goes to infinite, that is good and not the problem.

Now, leaving the one meter lead on the blue wire, take the other meter lead and probe the female contact for pin 87A on the fuse block for the Cool Fan S/P relay. The meter should read 0 just like on the test wire. Now take that lead and probe the female contact for pin 87 for the Cool Fan 1 relay. The meter should read 0 just like on the test wire. If the meter reads infinite for either of these tests you have an open in the blue wire somewhere between the LH fan and the fuse block.

Please post your results.

OldFart

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That thought got me also, that is why they run in low speed as they share the current, if there was an open in the RH motor getting to ground neither fan would work, I felt.

Which is why I was thinking that something is wrong with the RH fan, high resistance or a bearing problem binding it, but that would also blow a fuse. Maybe the contacts in the P/S relay can only carry so much current?, as they are burned and pitted? But then again he replaced it... Which means that there must be 12 volts to the motor but it drops,

Is this dropping with the motor connected?

Have you tested the current coming from the relay with the motor disconnected?

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You lost me, where are you getting pin #86, is that on my schematic? Talk in descriptions that adhear to that schematic I posted LH motor terminal "B" or "A", etc.... Am I missing something?

You should measure the resistance of each motor's primary wiring with the connector disconnected and see what you get. Maybe the motor is shorted internally.

If it is standard relay terminal numbering, 85 and 30 are the circuit open/close terminals and 86 and 87 power the coil. In this given situation with the 12+ readings, 30 would be the higher amperage 12+ supply and 86 would be the small amperage from the PCM powering the coil to close the relay. 87 should be a good ground and 85 should be closed to the fan's 12+ plug.

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Please post your results.

My results are as follows - I apologize that my response wasn't real clear last night; I also had some other things confused after re-reading these posts and the schematic. FWIW, the voltage drop was the "COOLFAN1" relay on the pin identified in photo 1 with the red arrow pointing to it. Now I get it, it says so right there on the schematic...I got confused because I followed the "LT BLU" wire to that relay and then interpreted that relay as "the one" for that fan. Embarassing.

Thanks for the tutorial on continuity, that was helpful.

OK,

1. Engine off, key off, LH fan wiring harness disconnected. When unplugged, I see "1" (infinite) when LT BLU compared to ground. When plugged into fan and compared to ground, I see continuity (0.00) in LT BLU. I also double-checked the black ground wire with ground and it read 0.00.

2. I did verify that RH fan runs even with LH unplugged entirely.

3. I did the pin 87a & 87 check (see photos on which pins I tested). Sorry, I cannot relate these pins in terms of the schematic. I went with the engraved mapping on the relay itself to determine which pins to check. Both 87 & 87a were infinite, so it sounds like there is a wiring problem b/wn fuse block and LH fan.

Would you recommend cutting the LT BLU wire a couple inches off the fuse block near the W/S washer reservoir and then running new 10AWG to the LH fan? I would say it's also be possible to splice into RH fan's power supply if that doesn't work, but I suppose that would cause an "always parallel" condition whether the PCM says so or not. Plus that seems hacky as I am not fixing the true issue.

That being said and given tonight's results, should I be checking the RH fan continuity out as well?

Thanks a million for sticking with me all. That's why I love this forum.

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<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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You should measure the resistance of each motor's primary wiring with the connector disconnected and see what you get. Maybe the motor is shorted internally.

OK, I just had my AHA moment. Regardless of whether the car is on or not, if it's a bad wiring scenario, I should be seeing "some" kind of conectivity between S/P relay and the hot wire for each fan.

Car off/key off:

I checked the LT BLU wire on LH fan, infinite resistance on ALL female receptacles of the S/P relay. I went ahead and checked them all to eliminate me choosing the wrong pin. Checked the WHT wire of the RH fan and got continuity (0.09) on pin #30 of the relay (which corresponds with Jeff's post #22). That is the "lower left hand" pin of the relay looking down at the fuse block from the RH fender corresponding with what's labeled #30 on the relay itself.

To me this says "with the car off, there is a verified connection between the WHT wire of the fan and the S/P relay. There is NOT a verified connection to the LH fan's LT BLU wire". Hence, the LT BLU wire is bad somewhere between the fuse block and the endpoint.

As far as I know, the wiring is connected to the fuse block via a crimped or soldered female end that ends up plugging into the fuses/relays/whatever that we readily see. My first instinct is that is probably not my primary cause and would want to first try connecting the LT BLU wire off the fuse block as early as possible where it's readily accessible.

I'll check back tomorrow before I get too far off the beaten path.

<!--fonto:Arial--><span style="font-family:Arial"><!--/fonto-->2007 DTS Performance - 50K

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As a matter of fact, I <i>am</i> driving 70 MPH in a phone booth.

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Correction:

Pin 87 should have continuity to the positive wire at the fan connector. Pin 30 should be 12+ and is the high amperage fused circuit. 85 and 86 power the relay coil (electromagnet). If 86 is a positive supply, then 85 would have to be negative...But one of those will be the switched circuit from the PCM. I would turn the car to on while cold. Don't start, and test those two pins to find which is constant. Then start and let the temp rise to temperature and test the switched circuit for power. That will at least answer that you are good to the relay in aspect of powering the relay.

Caddy_Grill.jpg2008 DTS
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