B1321

[Texas Jim]

I have access to 3 cases (12 cans per case) of R12... if anyone needs any.

[OynxSTS]

Update, and I'm not at all happy...

Ok a quick review... Car starts out fine... no codes 100% operational and FINE...

Car goes in to dealer for key fob programing... Key fobs work fine... but car is returned to me with Code B1321 CURRENT.

AC is off line... I suspect monkey business... I call dealer and they say NO way that a key fob programming could FuBar the BCM or A/C system...

Talk to independent mechanic #1 (at work) with top of the line 3rd party scanner... Scanner confirms B1321 and adds that refrigerant pressure is low. He agrees that key fob programming shouldn't cause any problems he says "Scanners are pretty much fool proof"

I buy two cans of R134a (and pressure gauge).. only to discover that the car has 160-180ish PSI (dependent on outside temp) on the low side with the compressor off. WELL within spec...

Talk to independent mechanic #2 (at trusted shop) we order a new OE refrigerant temperature sensor and I figure heck while we are there lets replace the pressure sensor too.. He evac's the refrigerant (the car had a full charge, NO leaks), he replaces the temperature sensor (and the presure sensor) they recharge the system and...yup... you guessed it... B1321 CURRENT! (insert several really BAD words here)

So back to the original question..

Is there anyway that the dealer could turn of the A/C system (either by accident or on purpose) and cause this error.

ALL other functions of the BCM are fine everything else is fine.. One code, and one code only, B1321... one problem, and one problem only... No A/C... all other functions work.

Ranger, anyone... Please help!

[Cadillac Jim]

B1321 A/C Low Side Temperature Sensor Fault

I don't see how they can do this programming the fob. Programming the fob talks to the IPM and possibly the RFA module while this DTC is all about the heater and A/C programmer, e.g. the ACM. I think it's either a separate problem (a coincidence) or somebody was looking at your car to figure out something about another car and accidentally fubared the connector.

This particular DTC isn't in my 1997 model year FSM, probably because it's self-explanatory. The first thing I would do is to look at the connector and make sure that somebody didn't lean on it with their hand to look at it to figure out a problem with another car, or jam a terminal pushing it back on, or some such. If the connector and all its terminals are good, then I would get out my multimeter and check the sensor (!!!), then look at the voltages on the connector.

Be *very* careful with the connector. I would use a DMM that is intended for use with static-sensitive semiconductor circuits here. Do not check resistance on the gray wire, and make sure that you are grounded when you look at the gray wire.

The black wire should be a ground. If the resistance to ground is more than a couple of tenths of an Ohm that is a problem that must be fixed.

The gray wire comes from terminal C6 (in my FSM) of the heater and A/C programmer, and with the sensor unplugged, should read +5 Volts. If it doesn't, then tracking this down will likely solve your problem.

With the sensor hooked up, the gray wire should read somewhere between 0 Volts and 5 Volts. This is the A/C low side temperature sensor input to the ACM. I would gather that this should read between a minimum of something like 1.5 Volts and a maximum of something like 4 Volts. If it doesn't, then the ACM will set a DTC.

[OynxSTS]

Connector and sensor are all good and all within expected resistances and voltages (as was the original)

I also measured the voltages at the BCM and again all are within expected ranges... VERY FRUSTRATING!

[JimD]

This might be nothing more than typing practice for me. But my Atlanta Braves are losing in the 12th inning and I'm here until the game is over!

I have (printed) Service Manuals for a 1998 Seville and a 2004 Deville. It is reasonable to expect the 1998 to 2004 Sevilles are similar if not the same (other than the engine differences that came about in 2000). My point is, the 1998 Seville Service Manual contains a troubleshooting page for B1321 and the 2004 Deville Service Manual has no such reference. And trust me on this, the 1998 to 2004 Sevilles and the 2000 to 2005 Devilles are more similar than different. My name is on the title for both models.

From the 1998 Seville Service Manual, B1321 is related to the A/C Low Side Temperature Sensor. Your posts have been mentioning A/C system pressure. A considerable difference.

The Low Side Temperature Sensor is connected directly to (and only to) the Dash Integration Module (DIM). Bottom line is, if the temperature sensor passes the test, the culprit is the DIM.

The Braves lost.

[OynxSTS]

This might be nothing more than typing practice for me. But my Atlanta Braves are losing in the 12th inning and I'm here until the game is over!

I have (printed) Service Manuals for a 1998 Seville and a 2004 Deville. It is reasonable to expect the 1998 to 2004 Sevilles are similar if not the same (other than the engine differences that came about in 2000). My point is, the 1998 Seville Service Manual contains a troubleshooting page for B1321 and the 2004 Deville Service Manual has no such reference. And trust me on this, the 1998 to 2004 Sevilles and the 2000 to 2005 Devilles are more similar than different. My name is on the title for both models.

From the 1998 Seville Service Manual, B1321 is related to the A/C Low Side Temperature Sensor. Your posts have been mentioning A/C system pressure. A considerable difference.

The Low Side Temperature Sensor is connected directly to (and only to) the Dash Integration Module (DIM). Bottom line is, if the temperature sensor passes the test, the culprit is the DIM.

The Braves lost.

Sorry about the Braves...

I have the FSM for the 2002 Sevilles and I have been focused on the refrigerant temperature sensor right from the start. It was a single third party scanner that said that the pressure was low too... wiring is all good... 5V is there as suggested... Voltage drop across the sensor was 1.8 Volts... right in the range that the FSM says it should.

The FSM says its one of two things... either the sensor (which was $17 and is now brand new) or the BCM.

The presure sensor was only $40 so I figure while there, replace that too.... turns out that the sensors are/were all good.

Ever see a BCM fail in one part in one tiny way? I think I might have.

Here is a different question... Does anyone know if you can "Re-Flash" a BCM? OR is the only way to fix this is to replace the whole freaking module?

[JimD]

Did I say Dash Integration Module (DIM)?

[OynxSTS]

Did I say Dash Integration Module (DIM)?

Sorry, ya DIM... It lives in the passenger foot well under the cover there... All of my voltage reading were at the DIM.

So back to my question...

Anyone ever see the DIM fail in one tiny way?

Any way to fix or "re-flash" the DIM or then a module replace.

What else does the DIM control? As I mentioned, everything else on the car is fine. 100%.

[Cadillac Jim]

The DIM is the module that is the master computer for the diagnostic mode, and, with the EBTCM, is the only module directly connected to the OBD II connector, according to my 1997 FSM section 8A-50. Thus if it's replaced then it must be flashed with the VIN and programmed with all the vehicle options and override codes.

If it's bad just because of one sensor reading, it's likely because of a back-probe on that sensor connector or some other abuse of that particular data line. These things don't go bad unless you ( a ) improperly exit after changing an override without storing it properly, setting a B1557 DTC may be set which bricks the IPM (1997 FSM p. 8C1-21), ( b ) electrical abuse of a line into the module such as a backprobe using the Ohms setting of a cheap meter or a static discharge, or ( c ) wholesale electrical abuse of the car such as connecting jumper cables backward or putting an 18+Volt fast charger on the battery with the cables still connecting the car to it.

If you are measuring voltages at the IPM that should not set a CURRENT code but are getting a CURRENT code (not either 5 Volts or 0 Volts while the key is on, say 1 Volt to 4 Volts), check out the module ground and everything else you can think of that might cause the problem.

There must be a chart of sensor voltage versus pressure somewhere but I don't see it in my 1997 FSM. Without that I can't say exactly what the "correct" range of voltages would be.

[OynxSTS]

When I get home tonight I will back probe the DIM again (with my $200 Digital Multi Meter ) and post the exact voltages with the new sensor in play... last time I checked it was 1.2 Volts (from memory) And it varries around that voltage dependant on ambiant temperature.

according to the 2002 FSM

Conditions for Setting the DTC:

• The DIM detects the signal circuit is less than 0.09 V or greater than 4.90 V.
  

Also it is interesting to note that the FSM goes on to say:

Action Taken When the DTC Sets:

• A default value of 5°C (41°F) will be used for the sensor data by the DIM to allow operation of the A/C system.
  
• The driver information center will display SERVICE A/C SYSTEM.
  

My car does the latter but NOT the former. On my car NO default is set, and the DIM NO LONGER ALLOWS opperation of the A/C system. Unlike is documented in the FSM, my A/C system is Off line. "The control plannel maintains a "A/C OFF" status, and will not engage.

[Cadillac Jim]

If the car is behaving differently than the DTC documentation says, then there are other faults. Sometimes a DTC will prevent other DTCs from being set. I think that there are other problems. Check the harness for connectors being hooked to the wrong sensor, particularly the low-side sensor connector being hooked to something else.

If there are other codes, any at all, let us know.

[OynxSTS]

If the car is behaving differently than the DTC documentation says, then there are other faults. Sometimes a DTC will prevent other DTCs from being set. I think that there are other problems. Check the harness for connectors being hooked to the wrong sensor, particularly the low-side sensor connector being hooked to something else.

If there are other codes, any at all, let us know.

Zero other codes and zero other defects

Will post the voltage after dinner.

[Ranger]

Not much I can add to what has already been said except that I doubt the dealer or anyone else could intentionally disable the A/C like this.

[OynxSTS]

Not much I can add to what has already been said except that I doubt the dealer or anyone else could intentionally disable the A/C like this.

Ya, I tend to believe that people as a whole are good... and that worst case here is that the dealer tech maybe did something.. By accident... Or this is just a weird co-incidence.

OK so I back probed Connector #2 on the DIM the black and gray wires in holes A6 & A7 and with the car sitting heat soaked in the evening sun I get 0.458 Volts... A little low, but again, with in the accepted range as per the FSM...(0.09 - 4.90V are OK) Looks like a dead DIM... grumble grumble...

Help me out Mr Ranger, sir, Is there any way to "re-flash" the dim?

...Could this have been caused by a tech un-plugging the TechII early? Or some other wonky thing?

[tdcrash63]

Was cruising through all the posts and noticed that you said 180 psi on the low side? If so system is overfull? Typical low side high side pressures with system at rest 85 to 105 psi. both the same. Possibly a mistype, bad reading if not way overfull?

[Ranger]

Help me out Mr Ranger, sir, Is there any way to "re-flash" the dim?

Not positive, but I don't think so.

Could this have been caused by a tech un-plugging the Tech II early? Or some other wonky thing?

Don't know the first thing about a Tech II, but I would not think so.

[Cadillac Jim]

Before I changed any more electronics I would put a full set of gauges on the A/C. If there is any doubt, I would recover the Freon, pump it down, and re-charge it to spec.

[OynxSTS]

Before I changed any more electronics I would put a full set of gauges on the A/C. If there is any doubt, I would recover the Freon, pump it down, and re-charge it to spec.

Thanks the suggestion.

That was done when they replaced the refrigerant temperature sensor... It is off to a different dealer next week.

[OynxSTS]

Update from the dealer...

"Wow that is a mystery isn't it"

Some good news first...

A/C checks out OK, Sensors all look good... Voltages all look good...

First thing he is going to try is replacing all of the connectors (which he has to order from Texas!).

He is confident that THAT is the problem, Well atleast the connectors are cheap.

He kinda sluffed it off when I pointed out that the FSM says the A/C should work with a default even with a bad connector...

He is VERY confident that its a bad connector... well that makes one of us...

Next update in a week.

[BodybyFisher]

Thanks for this insight, it will help us in our diagnosis. I would tend to trust his intuition, he may have experience that tells him that if all else is ok, suspect connections from age, corrosion, oxidation, wear from movement friction, etc.. This has been interesting to watch

[JimD]

....he may have experience that tells him that if all else is ok, suspect connections from age, corrosion, oxidation, wear from movement friction, etc.. This has been interesting to watch

My experience tells me if the electrical harnesses and connectors are all OK, only then can you suspect some other component. And OK'ing connectors can require a magnifying glass, a good light source, and quality time at the task.

From where I sit, I would question arbitrarily replacing all the connectors. Perhaps that is the most cost effective approach considering labor costs. Carpet bombs vs. sniper rifle.

Looking forward to the final report.

[BodybyFisher]

I agree, that he should only replace pertinent connections, how many did he say he was going to replace?

[OynxSTS]

I agree, that he should only replace pertinent connections, how many did he say he was going to replace?

Two.. The big blue one on the dim and the little black one on the sensor.

Fine, I'm at the point were I just want the car fixed ..

What is bugging me so far, is the diagnostic fee that I get nailed with...

I take the car in, I tell him that the A/C has a full charge and that has been confirmed by two different certified A/C techs (with a bill to prove it) I tell him that B1321 code points to the refrigerant temperature sensor and that is has been replaced (with a genuine GM part), That I have the old sensor, the bill and the little baggy that the new sensor came in to support all of that... I tell him that the DIM/BCM is not at all acting like the service manual says it should, that it is issuing code 1321 and that it is not defaulting to a setting that would enable AC... I tell him that I would like for him to put his best computer tech on this, and to see if the DIM is whacked or not. He carefully and dutifully writes this all down (types it into the computer actually)... I also tell him about the key fob programming and he agrees with everyone else so far... That was just a weird coincidence.

And when I pick up the car... I get a diagnostic fee that says:

Tested A/C (full charge, looks fine) Tested new sensor, passed, tested customers old sensor, passed, swapped in senor from part department, unable to clear code. wiring looks fine, DIM not operating as per specifications, suspect damaged connectors. 1 hour door rate $120.

The $120 is NOT the cost to replace the connector, the $120 is the cost to tell me everything that I told them. Now don't get me wrong, I'm not at all angry about this (ok a little grumpy... its more of an irony kinda thing)... I expect this is going to cost around a $1000 when we are all done... I just hope that they actually did some diagnostics on the DIM The tech II can see things that a mear human with a volt meter can't. There is a chance that the DIM is not getting full voltage for example... a bad relay somewhere could trigger this. It could have a bad ground... The techII can easily spot either of those problems.

If, (grumble *when* grumble) they replace the connectors and I get a second $120 diagnostic fee for a bad dim... then I'm going to be a little more grumpy.

Well to be fair... if they fix the car for the cost of DIM, the connectors, DIM programming and 2X $120 for telling me what I told them, then I will be happy as a pig in dirt.

[Cadillac Jim]

I think that the dealer service department may be reacting to what they are told by the service manager. It might be quicker and cheaper to just tell them that the A/C doesn't work and let them fix it for the flat rate for that job.

The logic is that by telling them specific things to check out that basically tells them to do things that aren't in the service flat rate manual, they are left with the hourly rate as the only reasonable basis for billing. It took about an hour and a half to verify all the things you told them to check out. But, they were told to do that but weren't told to fix it, apparently, but just to verify all the things that the service manager wrote into the service order. This apparently is what the service manager thought that you wanted them to do. He apparently didn't pick up the fact that you wanted the A/C fixed and you were just bringing all you had to his attention to help; this was a communications breakdown.

If you simply tell them to fix the car, they use the flat rate manual and the Goodwrench training and resources. The FSM isn't the Goodwrench documentation, it's just the tip of the iceberg. A good tech can and will fix anything, and will beat the time estimate in the flat rate manual.

That's the downside to knowing too much about your car. When you turn it over to a dealer, you need to let go and let them do the job their way. They are very good at that, but nobody but you knows how to do things your way. In going to a dealer with a good tech, you are hiring an expert to fix your car; trying to tell him how to work is inevitably worse than counterproductive.

[JimD]

....Well to be fair... if they fix the car for the cost of DIM, the connectors, DIM programming and 2X $120 for telling me what I told them, then I will be happy as a pig in dirt.

What has been discovered/resolved in the past nine days?