Crusader10hky

i've been visiting this forum often for its plethora of knowledge, but finally have to ask my own question.

I have a 92 that will not crank, has no LCD readout or backlight, no courtesy lights, ASM, ABS, and Service Engine Soon lights on.

I decided the common point of these problems was the CCM and assumed I had a bad ground somewhere. I performed all tests in the FSM troubleshooting guide for "CCM appears to be completely inoperative" and it points to a bad CCM. My understanding is that it is extremely rare to have a bad CCM so I'm wondering if I'm overlooking something.

I have the CCM removed to gain access to the plugs (per the previously mentioned FSM t/s guide). While I was there I confirmed that the ignition key pellet resistance showed the correct value to rule out VATS for the cranking issue. I also of course checked the fuses. What makes me less happy is the fact that I don't have any additional faults with the CCM removed vs. when the CCM is installed.

When i originally encountered this problem (in my in-law's driveway) I had it towed to my garage. It cranked but wouldn't start and I had all the other issues listed (including completely blank LCD). With no changes it randomely stopped attempting to crank.

What else could I check to confirm or rule out a bad CCM; Or better yet, start the car?

WVZR-1

It's pretty damn aggravating to remove a CCM.

You mention checking all fuses BUT I'd certainly suggest starting there again. I believe there are 3 related to the CCM. The LCD, the CCM and the AC fuses best I recall. Is this car an A4 or an M6? Can you easily connect the CCM and work with the CCM connected again.

Do you have a DVM and the proper diagnostic probes? Test light?

I'd reconnect the CCM after cleaning all of the connectors and make sure there aren't any problems with the connectors. As foolish as it might sound, I'd check the charge of the battery, confirm it's good and I'd probably remove the negative cable to allow the ECM to reset. I would think you disconnected the negative before doing the CCM removal but thought it maybe important to mention.

Is the radio stock and there's no after-market alarms or keyless entry?

What works? After CCM is connected what lights are on at "key-check" in the DIC?

'91 is first year for DAB. Does the DAB work as it should or not at all? You mentioned courtesy lights NOT working but with CCM installed "key-on", door closed, radio on and then removing key is radio still on until door is opened?

antfarmer2

did you check the fuseable links behind the battery?
and the block by the battery and fuse block if you have one?

FASTAZU

You can can read the codes, the CCM has its own set starting on page 8D-22 of your FSM.

Crusader10hky

You're tellin' me! First off I love this place. Where else can you get an educated response to a tough question about an almost 25 year old car in less than 12 hours? nice.

Second, and don't flame me for it, the car is a 1992 not a '91. That's what I get for speed-typing while tired. I feel shame.


Ok from the top:


I'll definitely check the fuses again, probably just replace them for good measure.


It is a 1992 LT1 with a 4 speed Automatic

I'm using a fairly high-end Digital Multimeter that I used during my time as an airline avionics tech. Admittedly, it does not put a load on the system while testing, but I did read 12vdc during the tests that asked if the 'test light' came on. I didn't have one handy.

The connectors showed no signs of damage or corrosion, but I used electrical contact cleaner anyway prior to my testing. I did have the negative battery cable disconnected during the removal. The battery is actually new and WAS well charged, but since the car hasn't started to keep it that way I now need to throw it on an external charger.

Stock radio, no aftermarket anything.

The DIC displays the same fault lights (listed in original post) with CCM connected or disconnected.

What works: under-hood courtesy lights, cabin fan for the air conditioning system and the A/C controller, headlight motors run their course when battery connected, Parking Brake light, Door ajar. Havent' noticed much else.

I did not test the DAB specifically. The relay for the DAB and the Starter relay are right next to each other. The one time that it DID crank I happened to notice the DAB relay closing as it should, but it is lifeless since. The CCM supplies the ground for the DAB relay. That's another thing that pointed me in that direction. Many things that receive their ground from the CCM are not working.


antrfarmer2- I didn't yet take the meter to the fuseable links by the battery, I'll hit that next.


We Gone- I don't own my own scanner. I would usually read codes off of the LCD, but I'm obviously unable to. I've got a cable on order for my laptop, but the slow boat from China is..well...slow.

antfarmer2

make sure to clean the terminal on the block behind the battery

Crusader10hky

Just an update.

I had a few free minutes last night so I cleaned up the ring terminals for the fusible links behind the battery to no avail.

Also, I decided to come at it from a different angle and troubleshoot just the blank LCD itself to see where it pointed. Used Chart #18 pg 8A-82-16 "Digital Display (LCD) does not light" I jumpered D8 of the Gray CCM connector to ground and the display lit up as bright as ever. The charted result was 'Replace the CCM' Just another nail in the coffin.

I have a good ground on C1 and E16, which are the 2 listed ground sources for the CCM. The only other thing I can think of to check would be the 'wake-up' signals. example: I should only have a ground on c11 when the key is inserted into the ignition switch and IGN in "off" or "acc".



Thinking ahead, anybody know a good place to buy a CCM? I'm thinking this won't be easy.

FASTAZU

Give this guy a call he may be able repair your CCM.

http://www.kandbcorvetteproducts.com/

Crusader10hky

I was thrilled this morning to receive a callback from K&B until he said "Oh, you need help with a CCM? Can't help you. The ICs (integrated circuits) I would need aren't available anymore. You'll have to hope to find a used CCM, then you'll lose all your mileage info."

That's what I was afraid of. Now, lets be clear, I would MUCH rather have a running car that I could enjoy, than a car that I could resell but not drive. That said, I won't be thrilled to have a CCM that doesn't match my VIN, Mileage, options, and passkey resistance. I saw in the FSM the instructions to program the key resistance to the CCM, but isn't that set in stone after the first 100 miles like the mileage? I doubt I'll be able to find a new, unprogrammed one. part number: 16159191

Just some basic searches turned this up (for almost $700), but the fact that they said no programming necessary and that it is Plug'n'play has me concerned. There's more to it than that right? I'll probably give them a call and have a chat, but who knows.

http://www.autoecmstore.com/products/16159188

-=Jeff=-

I know I have a 92 CCM.. set for a 6spd & Auto AC.. Maybe K&B can use it for parts?

I might have another that is a 92 auto (mileage unknown). I will need to look for them..

WVZR-1

Did you check either of these for "key resistance"? Did you note maybe the VIN for either?

-=Jeff=-

One is used, not sure of the VIN or Key resistance.. might be marked on it

the other while used I bought new for my 89-91 dash conversion. The VIN was my 89 VIN with the Year Letter changed to 92 to make it 'happy'. This one is the 92 6 spd

Although it had fits with communication to the ECM (ECM was 1990-1991). With this CCM, I did not make note of the Resistor value, but I have a key so I can get that info

Crusader10hky

That's actually something I asked K&B over the phone. I asked if I found another CCM could use parts from both to Frankestein one together. Unfortunately he said it would not work.

My 92 is an Automatic (and also has auto A/C). I've been told to make sure to use the same service number part (16159191) and to know what VATS key number is associated if I am to use a CCM from a different vehicle. My key is a 1.47kOhm (number 6 I believe?). My mileage is around 160,000 so I'm not really concerned about losing much value by running with a different CCM. I just want to drive it

I don't know how it would work to use a 6spd manual programmed CCM, anybody know?

WVZR-1

The CCM wouldn't care, I'm quite sure of that. If you had an "unknown" resistance but a match for the "service number" you could use a VATS Interrogator or create your own using a correct potentiometer. A 10K potentiometer will allow you to do all but the 15 KEY which is 11,800Ω, You would disconnect the lock cylinder wires, connect the Interrogator or potentiometer to the connector and "CRANK" using the key in the column now. Once solved just do another key with correct resistance matching your current mechanical cut OR a bypass of correct resistance.

MrWillys

Wouldn't a bad BCM cause similar symptoms?

WVZR-1

BCM/CCM same/similar component - engineering changed NOUN NAME in later production. When added to other cars and controlled more components/accessories BCM became the more popular acronym for Body Control Module. In the parts terminology I believe BCM is the terminology used for all.

MrWillys

Ah, thanks. My 2004 had similar symptom's last July after getting flooded in a parking lot in a thunderstorm. I removed the PC board from the BCM and could see corrosion on it and a water line height. WD 40 and a toothbrush and she fired right up. I did have to pull the PCM. The PC board was clean but the plugs had debris in them. I may have used some curse words during this process?

CCM really should have been kept because it is the heart of the car. Aren't the steering lock values different manual vs auto? Maybe it's a C5 thing.

-=Jeff=-

I will look if I get a chance today.. for the CCMs I have

-=Jeff=-

Yes C5 thing.. Steering lock on the C4 is mechanical, based off of switch position and a lock pin and lock plate in the column

Crusader10hky

Thanks!