[wtp]

I have a 90 bonniville sse w/3800 throwing a code 26. Any ideas what that might be. the book says quad driver. Any help would be great.

more info your engine side, mileage and fuel inj type.

[ghost71799]

If you don't have a book on that car, go to Autozone they sell Haynes manuals for that model.

Even better call Autozone and tell them the error code, make, model, year, and engine size, and they will tell you the problem.

If you don't have an Autozone where you live, call your local parts store retailer.

Ghost

[ido]

With the introduction of GM P4 ECMs, Delco Electronics changed to internally protected Quad Drivers. This internal protection can be compared to the action of a circuit breaker. If too much current flows in a controlled circuit, this type of Quad Driver turns itself off. This allows the Quad Driver to survive a shorted solenoid, relay, or harness. It also means you do not have to replace the ECM (expensive). Just repair the fault in the output circuit and the Quad Driver will return to normal operation.

Quad Driver #1 has the following connections at the ECM:

YC3--Canister Purge Solenoid
YC11--SES Light (Service Engine Soon)
YC2--Low Speed Fan relay

Quad Driver #2 has the following connections at the ECM:

BB5--High Speed Fan relay
YC15--A/C Relay

Quad Driver #3 has the following connections at the ECM:

YC9--Hot Light
YC10--Brake Light Switch and TCC Solenoid

Quad Driver #4 has the following connections at the ECM:

BD2--EGR1
BC2--EGR3
BC3--EGR2

All circuits except YC9 and YC11 should have battery voltage with engine running and the ALDL not grounded.

Code 26 accompanied by Quad Driver Mode codes 63, 64 or 65 usually require checking the EGR Flow circuits (common cause for setting this QDM code).