Computer issue
Thread Starter
Teching In
Joined: Sep 2007
Posts: 4
Likes: 0
From: Wichita, Ks.
Computer issue I bought a few years ago a computer from a wrecked 92 Vette to use swapping an lt1 into a 61 Belair. Things changed, I sold the car and had the computer in a closet. I sold it to a guy who says he ran a diagnostic check and all 3 quad Drivers are bad -it's useless. Could he have screwed it up plugging it in? He mentioned Elcamino so it's a swap setup. I'm not smart with electronics. I love Carbs and distributors -I can make them run in the dark with my eyes closed. Thanks for info in advance -Steve
TECH Veteran
Joined: Dec 2008
Posts: 4,145
Likes: 61
From: Little Rock, AR
Computers rarely go bad. I would be more likely to suspect that he is getting trouble codes because he does not have all the things hooked up that would normally be on a stock 92 'vette. The earlier computers don't have as sophisticated reporting codes as the later ones and the quad driver codes actually refer to many possible component failures at a time, rather than just one. The later flash PROM PCMs have individual codes for all those things.
It does not necessarily mean that the quad driver is bad and it would be more rare for 3 to be bad at once. He would need to get a custom chip burned to turn off error reporting for the things he does not have. That is standard procedure for anyone doing a swap.
To show you what I mean about the quad driver applications, here is a list of how it is on a 93 f-body ECM (I'm almost sure the 92 'vette is the same).
DTC26=
Quad-Driver Module (QDM) #1 circuit
applies to:
- AIR pump relay circuit
- EGR solenoid
- EVAP solenoid
DTC 27=
Quad-Driver Module (QDM) #2 circuit
applies to:
- 4L60 TCC control and temp switches
or
-T56 reverse lockout
DTC 28=
Quad-Driver Module (QDM) #3 circuit
applies to:
- fan control relays
- a/c relay
It does not necessarily mean that the quad driver is bad and it would be more rare for 3 to be bad at once. He would need to get a custom chip burned to turn off error reporting for the things he does not have. That is standard procedure for anyone doing a swap.
To show you what I mean about the quad driver applications, here is a list of how it is on a 93 f-body ECM (I'm almost sure the 92 'vette is the same).
DTC26=
Quad-Driver Module (QDM) #1 circuit
applies to:
- AIR pump relay circuit
- EGR solenoid
- EVAP solenoid
DTC 27=
Quad-Driver Module (QDM) #2 circuit
applies to:
- 4L60 TCC control and temp switches
or
-T56 reverse lockout
DTC 28=
Quad-Driver Module (QDM) #3 circuit
applies to:
- fan control relays
- a/c relay
Thread Starter
Teching In
Joined: Sep 2007
Posts: 4
Likes: 0
From: Wichita, Ks.
He said he checked it with an Actron diagnostic tool with his chip in it and the end result is that all 3 drivers are bad, his old one has one good driver. the swap isn't new, has been up and running for a time. so i guess i owe him his $$ back. thanks for the info, just wanted to make sure i wasn't getting screwed by him. Looks like I did by the guy
I got it from.
I got it from.
