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View Full Version : What is optional relay for in 89 6.2 GMC



simon
12-11-2006, 22:08
The other day I fixed the taillight wiring underneath my old truck. 89 Gmc 1500 ext cab 4x4 6.2 dsl.
When checking the signal lights with the ignition turned on all the gauges and instrument panel lights started flashing. I heard a relay clicking in tune with the flashing and traced it to be the one next to the the fuel pump relay.
After disconnecting it the flashing stopped. when reconnecting it everything was OK again.
Question: What is that relay for, on the cover it says optional relay.
I found that very informative? but still know dickall.
The service manual does not even mention that thingemedjingy.

could someone educate me here.

gmctd
12-12-2006, 12:28
Could be remote start or alarm relay - whatever it is, it should not apply p-p-p-power like that - may be a short in one of the circuits