Saturday, November 20, 2010

93 Seville 4.9- PO12 engine error?

Ok, here it is... I got a 93 seville 4.9 that keeps dying on me and giving a PO12 error. I know the error is no signal form distributor so , I changed cap , rotor , ignition. She fired right up, Drove her a while ashut her down and an hour later tried to start her and nothing. She turns and turns but wont fire. So I leave her for the night, come back, try her again and she fires up again???? WHY? Then leave her for an hour, and dead agian popping the same PO 12 errror. Now I have, tested the distributor coil, good, the ignition module is what I am down to and i hope that works. My question is this.....I sthe ignition module the same thing as the ignition swith? And....If the module change produces no results, where should I go next. And... How much roughly to rep[lace the ECM??? Thanks!93 Seville 4.9- PO12 engine error?
Your coil may still be bad even if it tests good, Heat may cause it to short or ground internally. Test it again.Test the pickup coil in the distributor the same way, cold and then again hot. If both of these test good then you can go to the module or computer. The module is the oblong black plastic item in the distributor. It has a connector from the pickup coil on one end, and a connector from the distributor harness on the other.93 Seville 4.9- PO12 engine error?
First of all I would stay with AC Delco parts. The ignition module is not the same as the ignition switch. When the car wont start try taping on the ecm with a screwdriver or wrench. It should be in the passenger side kick panel or behind the glove box. You also need either a cam signal or a crank signal to the ecm in order for the ecm to know whats going on so it can send a signal to fire. It most likley is a crank signal it needs and you will have to check that with a scope and volt meter but remeber the crank sensor produces AC voltage Before you go to far check for spark when it wont start just pull a plug wire and shove a screwdriver in the end and lay it close to metal on the engine and see if it jumps if you got spark then check for fuel pressure and easy way is to spray some carb cleaner down its throat to see if she goes then. I have had modules test good on the bench and fail under a heat load so never rule out the new part

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