trams am problem


Old 08-04-08, 07:54 PM
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Join Date: Aug 2008
Posts: 2
trams am problem

I have a code 26 guad driver fault set on a 1993 trans am. How do I diagnose the problem? There are no other codes set and the engine runs fine. The only other issue is a rich exhaust.
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Old 08-04-08, 08:18 PM
Unclediezel's Avatar
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
without a data stream view, you probably cant.

A quad driver is a section of your ECM , designed to handle High Current loads. These would include TCC, EGR solenoid, Cooling fan relay. etc.... There are 4 of them, (Hence the term "QUAD"), Designated by letters A Thru D. Without access to a data stream reading for which "Letter" has failed..your limited to grasping at straws , one at a time, until you find the failed component.

Logically, The Wiring to the EGR should be checked first, since a short to ground will trip a quad code, and an open EGR would cause a rich exhaust.
Old 08-05-08, 04:19 PM
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Join Date: Aug 2008
Posts: 2
I have a snap-on scanner so I can view the data stream. what should I be looking for? When I first aquired the car it had a code set for the EGR and an O2 sensor. I replaced the O2 and cleared the codes. After driving a couple of times the Quad driver fault appeared with no other codes. All the discriptions I have just dont show how to find the exact problem.

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