Hib Halverson
Technical Writer for Internet & Print Media
There are many helpful people here on the CAC and some of them have posted to this thread, however, some of the posts are based on L98 (85-91) troubleshooting techniques and the engine in question is a LT1 Gen 2 V8 not the L98. In some cases, L98 diagnostic techniques do not relate to LT1s.
DTC 26 is a "Quad Driver #1" fault. A quad driver is a device which controls four different actuators, in this case, the canister purge, EGR and ESV solenoids along with the relay which controls the AIR pump.
DTC32 is an EGR fault with a long and complex troubleshooting procedure.
To solve these codes yourself, you'll need the Factory Service Manual for 1992, a DMM, a 12v test light, a hand vacuum pump and a TECH1 or Mastertech scan tester with GM Powertrain software for 1992.
Since QDM #1 runs the EGR, it's understandable that if the QDM is faulty, then EGR would not work. Keep in mind that the QDM#1 being 'faulty" doesn't necessarily mean it needs to be replaced. There are wires and connections related to the QDM and a wires/connections problem in those harnesses or a bad ground could cause the QDM to not operate. The problem can also be the car's ECM.
Proper procedure in this situation is to solve DTC32 first then move on to DTC26.
My advice is to troubleshoot per the FSM before you start buying parts. If you don't have access to the above listed tools, I'd try to borrow or rent them and if you can't do that, I'd take the car to a service facility experienced with 92-up C4 electrical systems.
Good luck!
DTC 26 is a "Quad Driver #1" fault. A quad driver is a device which controls four different actuators, in this case, the canister purge, EGR and ESV solenoids along with the relay which controls the AIR pump.
DTC32 is an EGR fault with a long and complex troubleshooting procedure.
To solve these codes yourself, you'll need the Factory Service Manual for 1992, a DMM, a 12v test light, a hand vacuum pump and a TECH1 or Mastertech scan tester with GM Powertrain software for 1992.
Since QDM #1 runs the EGR, it's understandable that if the QDM is faulty, then EGR would not work. Keep in mind that the QDM#1 being 'faulty" doesn't necessarily mean it needs to be replaced. There are wires and connections related to the QDM and a wires/connections problem in those harnesses or a bad ground could cause the QDM to not operate. The problem can also be the car's ECM.
Proper procedure in this situation is to solve DTC32 first then move on to DTC26.
My advice is to troubleshoot per the FSM before you start buying parts. If you don't have access to the above listed tools, I'd try to borrow or rent them and if you can't do that, I'd take the car to a service facility experienced with 92-up C4 electrical systems.
Good luck!
