I have a 93 4 dr. Engine code tranlates to "low voltage from quad driver output module" Where do I look to find this? Car runs fine and there is no mention of this part on schematics I have

Please post the actual code -- we'll work from there.

Derf

I dont have the book in front of me but I believe it was code 26

In fact it isn't on all the time. Only when the car is fully warmed and I'm driving at 1500 rpm and up. When I stop at the light and the engine drops down to idle speed, then the light comes off.

Code 26 is quad driver output fault. Since the SES light behavior seems to be rpm related, I will forego the logical troubleshooting tree and guess, based on age of vehicle, oil consumption, etc, that your EGR valve is probably starting to stick --> check your EGR solenoid. Could be the EGR itself (probably needs a cleaning, especially if you have never done so before)

Derf

thanks, ill give it a try

By the way, what is a quad driver and how does it send a signal to the PCM . I guess if I know how it works I can figure out the problem without replacing parts until the problem goes away.

Mcgyver,
<TABLE cellSpacing=0 cellPadding=0 width="100%">
<T>
<TR>
<TD vAlign=top width=488 rowSpan=3>


Just because you have a Quad driver code doesn’t mean the Quad driver is bad. All a Quad driver code means is that an expected value is not present when it’s suppose to be. Also a Quad driver is a techy name for 4 on-off switches arranged in a group, hence the name Quad driver. The computer watches the voltage values on each switch and knows that if the switch is on, a voltage value will be seen. When the switch is off the opposite voltage value will be seen. Simply put, light on, light off. So what can set a quad driver code? You’d be surprised. How about a bad bulb? How about a bad fuse? The answer is yes to both questions. Yes, a bad bulb or failed fuse can set a Quad driver code. Start with checking your fuses. There can be up to 3 fuses that supply power to circuits controlled by the Quad drivers. If the fuses are good the next check would be of all or some of the following, depending on how your vehicle is equipped: Up shift light bulb, coolant hot bulb, shift to drive bulb, A/C relay, coolant fan relay, EGR solenoid, Canister Purge solenoid, even a speedometer output signal goes to one of the switches on the Quad driver. I guess what I’m saying is, that it is unlikely you have a computer problem. It’s more likely that the Quad driver code is present because the computer is not seeing the information that it expects to see at one of the switches.


Hope this Helps a little


Darryl T</TD>
<TD width=10></TD></TR></T></TABLE>

It helps alot. I assumed that if the solenoid for the EGR was powered but the circuit was open(ie open solenoid motor), that it would send a different resistance or voltage value back to the computer. I'll try checking the solenoid motor with a meter. All connections seem to be in check.