1998 Chrysler Concorde Auto Temp Control

Well, Bob, your kind words of encouragement have kept me from trading the beast in for a bicycle.

I did not drive the car as part of the clear/read code process. I did drive it plenty today, so I'll check for codes 1st thing in the am before heading off to work.

I have a friend who works in the automotive repair field and I'm sure he has a scan tool. I hate to have to ask him a favor where this is his livelihood, but it might save a ton of time if he can run some of the tests called out in this section of the manual.

I understand the methodical process they are using in the manual. I was an aviation electrician for 20 years in the Marine Corps and this is all very familiar to me in how they break the system down into chunks and then eliminate each with specific tests, even down to checking for opens and shorts and specific levels of voltage.

I'm hoping it will be a simple blower motor power control and ATC head. These, of course, are easy to access and replace. I'm afraid it might be the BCM, though, because of all of the sporatic indications I'm seeing. I know that everything runs through the BCM and it could very well be the culprit. At some point, I'll do the tests and find out one way or the other.

I've got too much time invested in this and am too tired of the A/C system blowing full blast all the time to give in now.

Re the 17A tests. To do the voltage and continuity checks, you have to remove the BCM from it's mount to verify several of the readings. If there was a way to do it without, I'd vote for that. But, I don't see that in the manual.

Thanks again for the encouragement. I'll track this puppy down, trust me.

Take care,
Bill

Progress!

I ran the ATC self diagnosis this am and it set only code 26, "ATC In-Vehicle Temperature Thermistor Failure".

Also, I've tracked down how to access and remove the BCM. According to the Technical Service Bulletin "AUTOMATIC TEMPERATURE CONTROL SYS. ERRATIC OPERATION", it only takes 0.4 hr to remove and replace the BCM. They don't know me very well. The reality is that this bulletin is very clearly written for accessing and removing the BCM. This will allow me to verify the operation of the Blower Motor Power Module via test 17A and eliminate that as a problem.

I did run across an interesting discussion in the above Tech Svc Bulletin indicating a possiblity that it could also be the BCM. I'm hoping not because of the cost of that beast.

At this point, my money is on:
1 - Blower Motor Power Module will test ok
2 - ATC head replacement has about an 80% chance of fixing problem.
3 - 20% chance of bad BCM.

Looks like my next chance to work on it will be Thursday night or Saturday. Saturday I also have to find out why it's taking our dryer over an hour to dry a load of clothes. That'll be a piece of cake compared to this.

Take care, Sir. More later.

Bill

Hey, Bob.

Re dryer. Could be any of those. I've been working on dryers, washers, refers, etc since the early 60s when my parents had an appliance repair shop. The automotive side (had an auto parts store too.) Was were I really felt at home. With luck it'll be something obvious and simple.

Have I mentioned I'm in the final stages of a bathroom remodel too.

Too many irons in the fire.

This Saturday, without fail, I will pin down what's going on with the car. That's a promise!

I commute too far for a bike ride these days. When I was younger, though, THAT would have been a different story. Used to ride 7 miles to hook up with friends in Santa Ana, then down to the beach, and then home at the end of the day. Did that several times and didn't think twice about it.

As soon as I have any more word on the car, I'll let you know.

Thanks for keeping the encouragement alive, Sir.

I DO appreciate it very much.

Take care,
Bill

3 for 3.

Hi Bob.

After looking behind the dryer, I decided that the exhaust hose was too kinked from the dryer being shoved back against the wall. Pulled it out to let the exhaust breath better. Will watch to see if results are acceptable.

Installed bathroom bifold door. Small trim project to finish off the window replacement to go.

Tore into the car. I followed the troubleshooting procedures as best as I could.
Here are some observations:

1 - Starting at 17A for the incorrect blower motor speed, it tells you to remove the BCM. However, the only way you'll ever find out how to do this is to stumble into the Technical Service Bulletin regarding the erratic operation of the ATC. In the bulletin, they have very clear instructions for removal of the BCM. If I've missed these instructions somewhere in the manual, I like my crow well done, thank you.

2 - These instructions are simple enough and should be part of the repair manual. Each step along the way of troubleshooting in 17A, except # 2, has you run the verification test. This requires reassembly and reinstallation of the removed parts and then running a complete retest of the whole system. For 17A, this would result in several removal and installation cycles. From past experience, the more you do something like this, the more likely it is you'll bugger something up.

3 - Where the wiring is the least likely problem and the blower motor power module is most likely to be the problem, when the blower only operates in high, it is a waste of time and a hassle to mess with the BCM at the beginning of the process. The final steps in 17A, where you connect a jumper to the red/light green wire of the blower motor power module 4-pin connector cuts to the heart of the matter. If the connector is shorted to ground and the blower still runs in the high speed mode, IT'S TH E BLOWER MOTOR POWER MODULE! If that test doesn't give the results you need, then work back toward the BCM.

When all was said and done, my fear of the BCM removal was based on ignorance of the actual process. If I had not stumbled into the Tech Service Bulletin, I'd probably still be standing in the driveway saying, " I don't really want to do this.. "

I've been in touch with an outfit that refurbishes the blower motor power modules to confirm they have the correct version for my car and will order it as soon as I've received confirmation they do. I'm 99% certain this will take care of the blower motor speed issue. Once that's under control, I'll turn to the ATC head. I'm certain that will just be a straight out replacement due to code 26 that keeps coming back.

I'm off on a business trip for three days. So I won't have anything to add to my saga until I get back and receive the replacement part for the blower.

I appreciate the help, the encouragement, and the just generally "being there" with me through this ordeal. I plan to add some nice, appropriate words as soon as the 2carpros forum calculates I have enough points to be allowed to do so. I tried last time and with only 0.9 points and it "chastised" me for only giving less than one point. :-(

I also plan to kick in some more to the "kitty" before I sign off for from this project. This has been worth every penny I've donated so far.

Take care sir.

And, yes, I do consult on dryer questions. ;-)

Bill

One down; one to go!

Hi Bob.

I replaced the blower motor control and now have control of the blower speed again.

The ATC head is still setting code 26, so I plan on ordering a rebuilt unit. The gent who runs the company that I ordered the blower motor control from also rebuilds the A/C heads. I ordered the blower motor control Tuesday and it arrived today. $10 shipping and handling anywhere in the U.S. Is a good deal when you're anxious to get the part and get the job done!

I'll let you know how the next stage goes. I have a trip next week to Tucson so I probably won't get to replace the ATC head until next Friday.

Take care,
Bill

Not good.

Hi Bob.

The ATC head arrived while I was away on my trip this week. When I got home last night, I installed the new one and it makes no difference in the operation. Basically, I'm where I was before the blower speed control failed.

I talked with the gent who supplied the replacement ATC head and we discussed the various possibilities. He thought there might be other temperature sensors, such as the sun load sensor (I think that's what it's called) up on the dash that could be driving the system nuts.

I mentioned that I thought the BCM might be an issue because of other things that are going on as well, such as interior lights going on and off randomly and the trunk release button not working. Another potential problem is a bad ground in the system somewhere. I shudder to think of a bad ground and trying to track that down.

I guess I'll try checking the bonding of the various parts of the car to see if there are any bad ones. The car does have a history of significant front end damage several years ago that could be the root of the problem. Push comes to shove, I may just order a replacement BCM to see if that helps at all.

I'll let you know how it goes.

Have a good weekend.

Bill

Update.

Hi Bob.

Because I don't have a lift to get the car into a reasonable working position, the concept of going for grounding points all over the engine compartment and the front end just didn't make my socks go up and down yesterday. I did, though confirm continuity from C2 pin 8 to dash ground and from the dash to the body of the car. I'm certain the BCM itself has a good ground.

Instead, I decided to take a look at one of the peripheral issues - the trunk release button inop. I tracked down the issue in the maintenance manual and printed out the troubleshooting procedure. The trunk releases just fine with the remote on the keychain but not from the release button in the dash. I've shorted the pins of the trunk release button connector to simulate the button being depressed with no results. I've measured the resistance across the button contacts and the button appears to be working fine. I went through procedure 12A for the Power Door Lock Test - Inoperative Decklid Release. The wiring continuity is fine from the button to the BCM and, obviously, from the BCM to the truck release itself. I didn't remove the BCM and short between pins 7 & 8 of the BCM 20 pin connector because I know the BCM is using that circuit to release the decklid when I use the remote on the key. That only leaves the BCM from what I see. Now, trust me, I wouldn't replace the BCM just because the trunk release button isn't working. I just see this as further confirmation of my suspicion that the BCM is not working correctly.

I just can't shake the feeling that the BCM is the root cause of all of these issues: ATC head not working correctly; interior lights going on and off by themselves concurrent with dimming/brightening of the dash/panel instruments and indicators; and trunk release not working. I'd love to be able to just plug in a new BCM just to see if it fixes these problems. Realistically, I know I can't afford that much just on a whim. On the other hand, I probably can justify one from a salvage yard, but that would be a pig-in-a-poke itself.

Tomorrow evening I might have a chance to talk with a friend who is a professional mechanic and ask if he may have one of the diagnostic tools that can query all of the various parts of the car. My OBD II just isn't designed to do the diagnosis I need for this issue.

I wish I still had my `64 Chevy.

I appreciate you continuing to monitor my saga and give me encouragement and suggestions.

True, True, TRUE!

The issue with a used BCM has been nagging me also. Before I'd buy one from a salvage yard, I'd have to have some kind of assurance that if I found problems with the used part, I could return it. I know for parts of this sort, that might be a tall order.

VIN - 2C3HD46J3WH259914

The Chrysler part number of the existing BCM is P04759532AK.

I've been told that numbers ending in either 32 or 34 would work. I've also seen in various forums, etc that years of 98 to 2000 for Chrysler Concordes, LSHs, 300Ms and Dodge Intrepids are compatible. Apparently, there is a difference between those with ATC and manual A/C control systems. The latter, I'm not positive about.

Here in SoCal, there are a couple of Pick-a-Part lots not too far away. They indicate that the cars are grouped by mfr so it wouldn't be too hard to find out if they have a model that might work. I've become fairly proficient in getting the BCM out so that's not a hindrance now.

It'll be interesting to see what kind of prices you find. One on-line source on the East coast is quoting from $100 to $150 plus shipping.

Take care, Sir.

Bill

Sure was quiet this week.

I don't have a clue why, but I never saw your two posts asking City/State info.

We're located in Santa Ana, CA and the beast is an Lxi.

I talked with my friend who is the professional mechanic and found out he's more of a mechanical systems guy, like brakes, air conditioning, engine, etc than an electronics or electrical guy.

He thought there might be a possibility that the BCM may have a software issue that could be corrected by reloading the firmware. I don't know if this is that style of computer or not. Could also be the software is loaded on a PROM. I haven't seen any indication in any of the troubleshooting sessions that talk about reloading the firmware, so I'm guessing it's using a PROM.

If the weather is cooperative, I think I'll make a run by Pick-a-Part tomorrow just to see if they have any cars in my year/model range that might work. If I can access the BCMs without removing them, I'll write down numbers to see if they are compatible or not. The trip has a secondary objective of locating a replacement center arm rest. My hinge and hardware crapped out a while back and I've been casually trying to figure out the best way to replace it. This will be two birds for one rock tomorrow.

Again, I'm sorry about missing your messages. I've been relying on email notifications from the web site but I guess I'll have to do a routine check for any new posts.

I'm still amazed that you're hanging in here on this project. Thanks again!

Take care,
Bill

We have options.

Hi Bob.

The trip to Pick-Your_Part was educational. For $2.00, I got to wander around and check out the various Chrysler products that fit the date range I'm looking for as a replacement for the BCM. I wrote down the model/year/VIN for each car at two different yards. All cars had the BCMs installed which is interesting. Seems no one wants or needs them, or at least not the used ones. The good news is they have a 30 day free exchange warranty.

I struck out on the arm rest which didn't surprise me. I think I'll try a traditional salvage yard where they have access to the computer network and can get input from many locations.

Any idea if there is such a thing as a cross-reference for the BCMs to see if several versions of cars are using the same part number?

Take care,
Bill