Guys Whats The One Under The Dash And What Does It Do?

 

It is the dumb question module. It causes posts like this. First, this is the C4 section. Is that where you intended to be? What year is the car in question? Where under the dash is it located? Does it have any markings? How many and what color wires plug into it? Can you give us just a LITTLE bit to go on?

RACE ON!!!

 

Ok sorry its a 93 vert that I have had so many issues with the ECM i AM NOT THAT KNOWLEDGEABLE ON C-4`s Car is at the dealers and have put 3 ecms on it and still will not run now they say its this module under the dash that will not let ECM COMMUNICATE.

 

VATS module perchance?

 

my guess is the ccm central control module, it is under center of dash controls alot of the interior functions, but if it is fried it cannot talk to ecm and car will not run

 

That sounds like the anti-communications module. Will the car display codes? Do you have any codes set? Follow the step by step trouble shooting charts in your factory service manual.

RACE ON!!!

 

Your talking about the CCM. It slides in, extremely tight tolerance, and mounts on two pins and a bracket.

It controls:
ambient light signal
chime
courtesy lamp
delayed accessory bus (windows audio)
dimming control (all dimmed lamps)
DIC (digital display, pke, diagnostics, oil monitor, fuel, instrument panel, etc)
PASS-key
PKE
rear defog
odometer
status warnings
system malfunction detection
system diagnostics
trip computer
UART serial bus master
Universal theft deterrent
speed detection

It's the master computer the other's are the slaves.

 

Thanks for the reply, The dealer is supposed to pull it and check 212.00 for the part and 2hr labor $88.00 per hour. I hope the fix it how hard is it to get to.

 

It's not that it's hard to get to, some contortion, it's the way its packed in there.

I thought I had a discounted price quote on the CCM but I can't find it. Anyway that sounds about right. And just 2hrs labor! It took me about 6 hrs to take it out, test a couple connections to the ECM and re-install it. I probably could do it in about 4 the second time. The problem is tolerance. The two main wire harness connectors are on the bottom side which compresses the wires into the carpet. There are lots of obstacles and you have to ease it out very carefuly a fraction of an inch at a time. I had to take numerous breaks.

I wonder if the got DTC's for loss of serial communcation data. There is also some test they can run using the Tech 1 that test the state of those two parallel serial lines from the CCM to the ECM. If new ECM's are not solving the CCM may be the issue. It's entirely possible.

 

there a heating module under there too, and an A?C vent module, and some vacuume modules. and a zillion relays..

 

These will help:

 

Jet jockey, awesome helpful response! Very much appreciated here! (that was me posting questions like that when I first joined here)
Awesome job. Thanx for being on this forum helping fellow Vette owners.

 

Your killin me,

 

No problem, glad I can be of assistance. That's what we are all here for.

 

Hi, nice pictures 93JetJocky
Can you please tell me if i need to disarm the Airbag system before you remove the CCM?

thanks in advance.

 

Nope your not messing with it. However, if your not comfortable pull the fuse but keep in mind the DERM still has enough energy stored to blow the bag. That's just FYI anyway.

All your removing is the carpeted knee pad, the knee brace, then you move over to the side of the console and remove the two torex screws that holds the hidden panel. Once there you'll see the mounting bracket. That comes out easy. Then the hard part of easing that module out. Sure those wires have a harness protector on them but still your so close on tolerance it causes the connectors to be very tight. So you have to be careful easing it out, like an 1/8 of an inch at a time. The trick to it, is when you think you want to pull down on the module to start it out the opening that's not right, instead you want to push up and keep coming out with it you start down at the last second. Like I said it was a pain and I had to take a lot of breaks. My chest hurt really bad the next day from leaning on the door sill.

Oh as it comes out and you have used up the slack in the closest connector you can now disconnect it, then continuing pulling it out until you can get to the next connector. Then you'll be able to pull it free. If I remember correctly I had it out of the location but the last connector was still on, then I removed it.

 

Thanks a lot, do you also have any wiring diagram för the wiring between CCM and ECM?

I have to find the fault that gives me the error codes "C41" "ERR" "H72"
It is not stated in my Chilton book..

 

Yeah no problem but it'll have to wait until this evening after work. I'm curious I thought the vehicle was at the dealer and they were swapping the module? If they swapped the ECM and the problem is still there, did they swap the CCM too? Are you saying the problem still exist now?

 

I have swapped the ECM myself because the ECM was bad, if i tapped the ECM with my fingers the car didn't go very well, so now after the swap the car runs fine, but this "service asr" lights come up and the "sys" light blinking, when this occurs i have problem to start the car if i turn it off. I think there is some bad wiring between CCM vs ECM..

 

Excuse my ignorance, but are you talking about the module that they plug their scan-tool into? If so, have them take a mild steel brush and remove the corrosion from the terminals. Worked for me.