Well, no more problems with the EGR valve, but now I'm getting a persistant intermittent code 26. Does anyone know what usually causes the ECM to spit out a code 26? What is the quad driver circuit? If anyone has answers to these questions, let me know, because I'm stumped!

A bit of digging around, I found this.



It came from this site
http://autorepair.about.com/library/faqs/bl012i.htm


From what I understand, it is the ECM that is in protection mode cause a relay or solenoid is shorted out somewhere. I did see some kid of mention about the tranny also ( wiring)

i fixed my code 26 on my 92 by replacing the Evap Canister Purg solinoid under the airbox behind the headlamp. 26 i know is also if you SES light doesnt work, or your TCC lockup isnt working

sse1990, that'* for a vin L, which is an L27 i think? But 26 is the quad driver circuit nonetheless, which controls brake switch, tcc solenoid, evap system solenoid, and something else i think?

I had an intermittentant code 26 whenever the car would stay in 2nd [my trans is blown and only has up to 2nd gear], so after being in 2nd gear for about 5 seconds the SES light would pop on and stay on until i'd drop my speed to 1st gear range.

I guess I forgot to include that I have an '89 Bonneville SSE with about 230,000 miles on it. I am aware of a grounding problem with an aftemarket CD Changer I installed in my car. From what I see on that info sheet, the ECM might be in protection mode due to an overload on a particular circuit. Is it possible that this could be related to the grounding problem? Could something be shorting out my ECM ...?

Davinci, did you ever fix this? Mine does the same thing. 1990 LE 77k miles throws a code 26 pretty often, but it doesn't seem to be at any specific time of the drive. Sometimes after it'* first started, sometimes after throttle lift at highway speed, it seems to be at different times. I have narrowed it down, thanks to learning on this forum what quad driver does. Chilton'* was no help at all here. I'd rather not just change out parts if I don't really have to.

It hasn't thrown any more codes recently. The only thing I changed before it stopped is switching to synthetic oil. Also the weather has gotten cooler. Could this possibly be related?

Well, right now, I'm busy replacing my crank pulley (you know - the infamously deceptive rattling from the drive belt side of the engine). The SES light is currently on permanantly with the code 26 ... so far it hasn't affected the driveability of the car, though, so I'm not too concerned about it right now. I got bigger fish to fry!

I also changed my pulley. Is there any possible way these problems are related?
I'm getting a code 26 very rarely now, at 81,000 miles. But it is still doing it. It seems to be tripping the SES light when I come to a stop after having driven for a while. There doesn't seem to be any driveability problems. Runs good.

It looks like I need one of these too. Can you tell me where you got yours and how much you paid for it? Thanks.