Is there a jumper I must short or what to read Codes from this machine? My
grandmother has had her engine light lit for some time, and I don't think
her garage has figured it out?!?
Also, for several years the Check Guages indicator is lit. What exactly
trips that, is it an individual signal from each guage or fed from a
Nice little car, 60,000 miles.
Any sites or assistance appreciated.
According to the Haynes Repair Manual, "on some OBD 1 models with a 12-pin Data
Link Connector, trouble codes can be accessed by connecting terminal B with
terminal A with a jumper wire with the ignition key in the ON position and the
codes can be read by watching the flashes of the SERVICE ENGINE SOON light."
Do not crank or start the engine when terminals A and B are connected, the ECM
could be damaged.
The pin layout is F E D C B A
G H J K L M
A is ground, B is the diagnostic test terminal.
The book also says that some models with the 12-pin connector do not have a
terminal B present. In that case you'll need a scan tool.
I can tell you that I have owned 2 Pontiac Grand Prix's, a 1991 and a 1992,
and both had dash lights on that were on for no reason. I heard that dash
boards of that era were faulty at times, such as on my cars, where the Check
Gauges and Low Fuel lights were on all the time. Also, the Oil Pressure
gauge did not work on either car, and does not work on my '91 Bonnie either.
Some GM vehicles had problems with the cluster-controlled lights such as
Check Gauges behaving erratically because of bad solder joints on the
cluster PCB, but the Check Engine light is always controlled directly by the
Robert Hancock Saskatoon, SK, Canada
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