Jim Grant's Tech Tips
'90 Corvette, Air Bag Fuse
Q:
I’m having to deal with a short of some kind that is located on the
Air Bag circuit of my ‘90 Chevy Corvette. I have eliminated all air
bag connections except the main one from the DERM. If this connection
is not made , the car will not run. The car will start and you can drive
it about a quarter mile and it will blow the air bag fuse. I think there’s
something else on this circuit that is really causing the problem, but
I do not have an electrical schematic that details the air bag fuse circuit.
Anyway , when the fuse blows, the engine cuts out. I put a new fuse in
and it starts up , I go a short distance and it blows another fuse. Hope
you can help.
A: The
Air Bag fuse on you vehicle just happens to be tied in with the vehicle’s
engine computer and a relay or two. After reviewing the wiring diagrams
for your Vette it was easy to see that GM did not intend to make it easy
for someone to disable their vehicle’s Air Bag system. Here are a
couple of items you should check for possible causes for fuse failure.
The canister purge solenoid and the electric air pump relay; both units
are powered by the Air Bag fuse. A shorted electrical winding in either
unit would be cause for fuse failure. The Diagnostic Energy Reserve Module
(DERM) which is the operational and in/during crash recorder for the Air
Bag system is not known for ripping fuses but it is possible. There is
an isolation/diagnostic procedure of all the systems that the Air Bag
fuse powers. But they should be performed, by a technician that is knowledgeable.
Why? Because if you jump the wrong wires, you’ll let the costly magic
smoke out of the vehicle’s computer..
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