wrong MIL bulb lights to flash out DTC's in 94 Suburban?

Question

I jumpered A&B on the data link connector to get the "service engine soon" (MIL) light to try to blink out the diagnostic trouble codes. (The thing lights after driving for 10 minutes and then usually turns off after 20 more minutes. I suspect an EGR issue.)

Anyway, with A&B jumpered, the "ABS Antilock" indicator does the blinking of code 12 ("system working") over and over again, nothing more. The service manual says the "service engine soon" bulb is supposed to be doing the blinking. What gives?

Steve W. · Accepted Answer

94 Surburban with a 5.7? Probably NOT OBD I, That was a changeover year on the Sub. You will need a scanner to read the codes.

hillpc · Answer

The service manual claims one doesn't need a scanner.

Scott Dorsey · Answer

I think by '94, you need the scanner.  Older models didn't require it. --scott

Steve W. · Answer

The problem is that 94-95 were change over years for auto makers. SOME model/engine combinations used a mixed OBD system. They had the old style ALDL but different hardware and software in the system. No way to read those codes without a scanner.

The 94 Suburban shows up in the books as both an OBD I and OBD II depending on which engine it has.

Paul · Answer

It is possible that you will need a scanner.  Especially if it was made in 1994.  "NOTE: Some 94 & 95 models that DO have the A & B terminals still require ascanner."

hillpc · Answer

Thanks, guys.  Now I'm curious about the ABS light blinking a 12 pattern when I jumper A&B.  I'll probably disconnect a wheel sensor and see if it blinks out something else now.

wrong MIL bulb lights to flash out DTC's in 94 Suburban?

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