2000 Seville (STS) - LH cooling fan not running

[OldFart]

Mark, you are on the right track and have identified you have an open in the LT BLU circuit. You can bypass the LT BLU wire as you mentioned, or you can troubleshoot a little further and find the open and repair it.

According to the schematic there is another connector before the fuse block. It is identified as connector C1. Look at the schematic and follow the LT BLU wire up to where it enters the fuse block, at that point the LT BLU wire is identified as pin "E10" in connector "C1". If you can find that connector and disconnect it you can meter between 87A on the S/P relay and pin E10 on connector C1, it should read 0 ohms. If not the problem is between connector C1 and the fuse block. Also meter between E10 on connector C1 and the LT BLU wire at the fans plug, again it should read 0 ohms, if not the problem is between connectr C1 and the fans plug. Unfortunately I have no idea where this connector is located or what it looks like.

Sometimes the problem can be inside the connector itself, or even possibly an internal break of the wire. Since you had the radiator replaced in 2009 it is also a possibility a wire got pinched and finally worked its way to severe the wire. Check the entire route of the wiring harness paying close attention to any place it comes in contact with something else and hopefully the open (and/or break) in the wire will be obvious.

As a genral rule, all connectors on our cars have the pins labeled, albeit sometimes real small and difficult to read. Sometimes it is engraved on the outside on the connector, sometimes you have to look directly at the pins themselves. Look at the plug for the LH fan and I'll bet you will find the LT BLU wires pin is labeled "B" and the BLK wires pin is labeled "A" just like on the schematic.

[cadillacjeff7777]

Mark, you are on the right track and have identified you have an open in the LT BLU circuit. You can bypass the LT BLU wire as you mentioned, or you can troubleshoot a little further and find the open and repair it.

According to the schematic there is another connector before the fuse block. It is identified as connector C1. Look at the schematic and follow the LT BLU wire up to where it enters the fuse block, at that point the LT BLU wire is identified as pin "E10" in connector "C1". If you can find that connector and disconnect it you can meter between 87A on the S/P relay and pin E10 on connector C1, it should read 0 ohms. If not the problem is between connector C1 and the fuse block. Also meter between E10 on connector C1 and the LT BLU wire at the fans plug, again it should read 0 ohms, if not the problem is between connectr C1 and the fans plug. Unfortunately I have no idea where this connector is located or what it looks like.

Sometimes the problem can be inside the connector itself, or even possibly an internal break of the wire. Since you had the radiator replaced in 2009 it is also a possibility a wire got pinched and finally worked its way to severe the wire. Check the entire route of the wiring harness paying close attention to any place it comes in contact with something else and hopefully the open (and/or break) in the wire will be obvious.

As a genral rule, all connectors on our cars have the pins labeled, albeit sometimes real small and difficult to read. Sometimes it is engraved on the outside on the connector, sometimes you have to look directly at the pins themselves. Look at the plug for the LH fan and I'll bet you will find the LT BLU wires pin is labeled "B" and the BLK wires pin is labeled "A" just like on the schematic.

87a is used? I believe ya. Just a little disoriented I guess. I don't know the wiring as you do but was speaking in general function of the relay. 87a should be a normally closed circuit within the relay to terminal 30 and only opens the circuit upon a charge being applied to 85 and 86. That would mean that the relay has power applied and is charged at all times that the fan is not required.

Thoughts?

[OldFart]

87a is used? I believe ya. Just a little disoriented I guess. I don't know the wiring as you do but was speaking in general function of the relay. 87a should be a normally closed circuit within the relay to terminal 30 and only opens the circuit upon a charge being applied to 85 and 86. That would mean that the relay has power applied and is charged at all times that the fan is not required.

Thoughts?

Your thoughts are correct as well Jeff, however not applicable with the open in the LT BLU circuit that he has. The relay in particular Mark is working with is the S/P (series/parallel) relay. It is feeding positive voltage from contact 30 thru 87a with the relay de-energized. The low speed and high speed relays do not utilize terminal 87a, only terminal 87 when the relays are energized. The S/P relay when de-energized has both fans in series resulting in low speed operation. When the relay is energized the S/P relay puts the fans in parallel (pin 30 routes thru pin 87 directly to ground) resulting in high speed operation.

Mark confirmed that he does not have continuity from 87a on the S/P relay to the fan motor, now he needs to find the open in the wiring. Based on Marks posts he has confirmed the relays are working and have the source voltage on the correct terminals, just not getting the voltage to the fan.

[Jimindyv8]

Did anyone find the fix/solution? I have this exact problem.

[mmarinov]

Jimindyv8,

Unfortunately I did not find the root cause. I had to make a judgement call on this one and decided to bypass the wire to get the fan running. My decision may have been different today, but at the time it was a $5,000 car with nearly 100K on it and I had to pick my battles.

I will be honest and tell you that I traded my STS in about a month after this post in 2011 (NOT related to this repair, just coincidental). I had to drive about 200 miles from where I live to the dealership where I bought my DTS, and it ran cool as a cucumber. Previous to me jumping the wire (so, one fan), the STS was darn near overheating several times. Twice I received "ENGINE TEMP AC OFF" or something to that effect on the DIC.

Full disclosure - I did not take the STS into the dealership for any further diagnostics.

Mark

[Cadillac Jim]

It was probably a fan relay, if jumpering the fan made it run. This kind of thing should be routine to anyone reconditioning a used car for resale, so I wouldn't worry about it.

[BodybyFisher]

Did anyone find the fix/solution? I have this exact problem.

Check for CODES that are set, the fans WILL set codes to help in the diagnosis.

There is NO "fix/solution" to this problem because the cause has not been diagnosed. The fan not running can be caused by a bunch of things and it needs diagnosing. Here are a few possibilities, bad fan, bad relay or relay connections or bad wiring, bad connector. First, I would remove the fan, and connect 12 volts to it making sure that you keep positive and negative straight. If the fan runs you can eliminate the fan as a cause, if the fan does not run, get a new fan, I have seen bad fans. Then, without having a TECH 2 to energize the fan, I would get the fans to run buy covering radiator/AC condenser air stream in front of the radiator with cardboard with the engine running to get the temp up till the fans are commanded on full, which is about 227 degrees in the winter months, have a voltmeter connected to the fan connector and see if you get power to the fan connector, the other fan should start running when the temp is 227 and at that point you should have power. You will inspect the connector male and female sides while the fan is out for corrosion or burnt connectors, etc. If you get no power when the temp turns on the other fan, I would check the fan relay connectors and test the relays to see if its connectors are corroded or the relay is bad. There are 3 relays grouped together straight down in the middle of the car behind the fans on a cross member if you look down. The relay contacts can become corroded from getting wet interfering with a solid electrical connection.

[Cadillac Jim]

He traded the car right after the last post in 2011. I was just reassuring him that he didn't do a bad thing by not fixing it first, or bothering to give the dealer a heads-up.

[BodybyFisher]

Did anyone find the fix/solution? I have this exact problem.

I was replying to this guy who just posted the other day.

[Cadillac Jim]

Oh. Then, we need to hear back from Jimindyv8.

No, the original poster traded the car before he solved the problem. But fan problems are not difficult to diagnose and everything is easy to get to. See BBF's post.

[BodybyFisher]

Here is what the three relays look like down under the cooling fans in the center. Notice that the one on the left has a missing "catch", this can allow the connector to back out from vibration. When I make my next trip to the scrap yard, a replacement is on my list.

[Cadillac Jim]

Jimindyv8, If one fan is running and the other is not, it still could be either a fan or a relay. You really do need to run the OBD codes.

The three relays in BBF's post work together to turn the fans on hooked in series (LOW speed) or both hooked to battery and ground (HIGH speed). They are operated by the PCM which reads the engine temperature from a sensor.

There are some things to test that may help, but to be sure what's up you still should run the codes before buying parts. When you are done, you will need to run the codes to be sure that you are done. See the link in my signature block for a link to a Caddyinfo how-to page on running your codes.

Things you can do to tell whether it's a relay or a fan:

• When it's cold and the A/C is OFF, the fans should not run. With the A/C ON, both fans should run at LOW speed. If one fan runs at HIGH speed, then the fan that is not running is shorted. If the working fan runs at LOW speed, the other fan is stuck or jammed. A short could still be in the wiring, not the fan.
• Even with the A/C OFF, when the engine temperature gets to 229 F (106 C), the temp gauge at about 1:00 PM, both fans should run at LOW speed.
• When the engine temperature gets to 234 F (112 C), the temp gauge at about 2:00 PM, both fans should run on HIGH speed, regardless of whether the A/C is ON or OFF.