CamaroCasanova

1994 TA LT1-belongs to brother in law. It has a new GM opti, new opti harness, new ignition control module, new wires, new plugs, and coil. The car will not start. We cannot figure out why. I am at my wits end trying to figure out why it will not start. The only code it throws is 42 now. Oh yeah, new fuel pump and filter too. Doesn't even pop over. I am sure the opti is on there right, plug wires are sequenced correctly, so we are at a dead end. I am now thinking a wiring issue somewhere.

Any help or experience sharing would be very appreciated.

Injuneer

DTC 42 indicates a grounded IC Module circuit. There's a fairly detailed diagnostic logic chart in the factory manual. Shoebox may have a copy of it on his website, or I could fax or e-mail a copy of it.

Have you also verified that the Opti was correctly installed with the missing tooth on the splined drive shaft in the correct orientation? Many people answer "yes" to this question, only to find later the correct answer was "no".

CamaroCasanova

Over and over again I think it may be installed improperly even though I also say "yes" I thought we had it in there right. I know they can go on there wrong. I am going to try it again. If that doesn't work I would love someone to give me a copy of the diagnostic chart.

sabre81

any updates????

i have pretty much the exact same issue but i also get code 36. Could a mis aligned opti drive pin cause codes to be thrown? The opti slid in very easy... could it still be installed wrong?

MEAN LT1

Oh so very true.