Do I need a new CCM??
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Joined: Apr 2005
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From: Boynton Beach, FL
Do I need a new CCM??
After sitting for a week I tried to start my 93. Dash lit up and then went blank, no starter engagement. This happened 3 times. On 4th try car started up and ran fine. I drove the car all evening and I had a SYS ERROR on display that went away next time I started car. The next morning I pulled CCM codes and got an H31, H33, H35 and H37 code. All 4 codes are related to the data communication between the CCM and the LCD display. On start, the CCM is supposed to pull all four circuits to ground. Re the manual, the common error fault cause between these circuits is an open in the CCM. I probably have an intermittant open in the CCM PCB or the driver/transister that supposed to pull these 4 circuits to ground is going flaky. Is the CCM fixable? Does`anyone know how to get a schematic? If I change the CCM, does it have to be programmed? I HATE COMPUTER CARS!!!!
Larry
Larry
Safety Car
Joined: May 1999
Posts: 3,651
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From: Atlantis
Cruise-In I Veteran
I've looked far and wide and have never seen a schematic for the CCM.
When you replace it you have to have it programmed with your VIN # or it will die after.... heck I forgot how far but it's not far at all, 100 miles???? SOmething like that... I think it has to be done with a Tech I ot II analysis system.
I think the only valuable thing it does on my '91 is; reads the door switches, the key pellet, makes the interior lights work and runs the digital speedo, trip meter and mileage indicator.
A small PIC chip could handle most of that with ease. (and put ME in control
)
A CCM is NOT needed to run the 730 or 727 ECM standalone. Iv wired up a SD system with the 727 weatherpack ECM on my '73 Chevy Super Cheyenne pickup. My ECM is happy as a lark with no CCM.
All my truck gauges are analog however.
Note: I LOVE computer cars. They are MUCH easier to fix than no-computer cars.
Once you get used to them you'll love'em too. I'm not too enamored of the CCM system though.
It's in a horrendous place to do any troubleshooting. What eh HECK were they thinking when they put it there???
That 'little transistor' is likely residing inside a little plastic package with 32 or 64 pins on it.
Makes'em pretty hard to replace even for a determined guy like me.
When you replace it you have to have it programmed with your VIN # or it will die after.... heck I forgot how far but it's not far at all, 100 miles???? SOmething like that... I think it has to be done with a Tech I ot II analysis system.
I think the only valuable thing it does on my '91 is; reads the door switches, the key pellet, makes the interior lights work and runs the digital speedo, trip meter and mileage indicator.
A small PIC chip could handle most of that with ease. (and put ME in control
)A CCM is NOT needed to run the 730 or 727 ECM standalone. Iv wired up a SD system with the 727 weatherpack ECM on my '73 Chevy Super Cheyenne pickup. My ECM is happy as a lark with no CCM.
All my truck gauges are analog however.
Note: I LOVE computer cars. They are MUCH easier to fix than no-computer cars.
Once you get used to them you'll love'em too. I'm not too enamored of the CCM system though.
It's in a horrendous place to do any troubleshooting. What eh HECK were they thinking when they put it there???
That 'little transistor' is likely residing inside a little plastic package with 32 or 64 pins on it.
Makes'em pretty hard to replace even for a determined guy like me.
Last edited by VetNutJim; Mar 4, 2007 at 11:35 PM.
Thread Starter
Pro
Joined: Apr 2005
Posts: 590
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From: Boynton Beach, FL
Battery is a year old and is on a Battery Tender trickle charger when stored for a week. I will check the battery connections though. It's possible they need cleaning although I doubt it.
Larry
Larry
