93 LT1,no firing...
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Joined: Oct 2017
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From: Taule Bretagne
93 LT1,no firing...
Hello everybody ,
I have a 93 Corvette 190,000 miles ,after automatic box overhauled ,and various settings ,TV cable ...........oil sensor ,throttle cable (but is not very stiff now ) ,i "try to use my car .......After 1/4 mile ,rpm engine was hesitating ,RPM going up and down ,but I succeed to be back home ,(I was supposing not enough fuel ° .Put more fuel ,and after 2 miles same thing again,rpm up and down ,some misfiring nand stall middle road ,not possible to fire again .Home I replace opti (AC 4,00 miles )with Petris vbentilated ,coil ,ICM ,finlly no starts.....so I have "played " withy codes erasing ,and I got C 12 only ,sparks at coil and fire in the second (as before) ,so before installed back WP ,many starts in the second.Pump back ,some difficulties to fire ,and then fire .I leave engine running until cooling fans start about 180,rpm 500 as usual,running steady ,and after 20 minutes,rpm up and down ,some misfiring ,and stall again ,since not any starts .Codes are H16,H41,H72 ;After aga
After looking to FSM ,,the conclusion
I have a 93 Corvette 190,000 miles ,after automatic box overhauled ,and various settings ,TV cable ...........oil sensor ,throttle cable (but is not very stiff now ) ,i "try to use my car .......After 1/4 mile ,rpm engine was hesitating ,RPM going up and down ,but I succeed to be back home ,(I was supposing not enough fuel ° .Put more fuel ,and after 2 miles same thing again,rpm up and down ,some misfiring nand stall middle road ,not possible to fire again .Home I replace opti (AC 4,00 miles )with Petris vbentilated ,coil ,ICM ,finlly no starts.....so I have "played " withy codes erasing ,and I got C 12 only ,sparks at coil and fire in the second (as before) ,so before installed back WP ,many starts in the second.Pump back ,some difficulties to fire ,and then fire .I leave engine running until cooling fans start about 180,rpm 500 as usual,running steady ,and after 20 minutes,rpm up and down ,some misfiring ,and stall again ,since not any starts .Codes are H16,H41,H72 ;After aga
After looking to FSM ,,the conclusion
Thread Starter
Intermediate
Joined: Oct 2017
Posts: 37
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From: Taule Bretagne
93 LT 1 no firing
The conclusion is ,"open circuit between ECM and ICM.......Another test this afternoon ,code checks ,only C 12 .Try starts ,no ,codes now H16,so my story is not finshed ...If somebody got ideas ..what bother me ,is before opti renewal ,and after renewal ,STILL same problems .Thanks for help............
Thread Starter
Intermediate
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From: Taule Bretagne
Thank you ,for your replies ,
For my repair ,box ,I run with ,about 5,00 miles ;without problems ,and not any miss firings .As FSM ,says that maybe "open IC circuit between ECM and ICM " ,for me it's hard to believe ,,because when you check harness form ECM up to ICM ,it's very hard to see something ,and harness ,is not in contact with engine hot parts .I will check again this afternoon .
After looking to forums ,,I was convince that problem comes from ECM .But before to send to US from France I want to be sure ,money wise ...I will let you know ,later on .news
For my repair ,box ,I run with ,about 5,00 miles ;without problems ,and not any miss firings .As FSM ,says that maybe "open IC circuit between ECM and ICM " ,for me it's hard to believe ,,because when you check harness form ECM up to ICM ,it's very hard to see something ,and harness ,is not in contact with engine hot parts .I will check again this afternoon .
After looking to forums ,,I was convince that problem comes from ECM .But before to send to US from France I want to be sure ,money wise ...I will let you know ,later on .news
Le Mans Master
Joined: Aug 2015
Posts: 6,119
Likes: 1,997
From: St. Charles MO
Hzve you tested the wire that leads from the ECM to the ICM for continuity? That would be the very first thing I would check. If that wire has minimal resistance, then it's okay. But if it's infinite, then it's an open circuit and won't work. If it's an open circuit, then run a new wire and see if it will run.
Also, look at the harness where it connects to the ECM. Make sure the little metal connector that contacts the ECM pin for that wire is still physically in the connector. It should not be loose or halfway out. Make sure it looks like all the other connectors.
I agree that it's possible for the ECM to fail, but I would expect more than just the output signal the ICM to have failed if that were problem.
Also, look at the harness where it connects to the ECM. Make sure the little metal connector that contacts the ECM pin for that wire is still physically in the connector. It should not be loose or halfway out. Make sure it looks like all the other connectors.
I agree that it's possible for the ECM to fail, but I would expect more than just the output signal the ICM to have failed if that were problem.
Thread Starter
Intermediate
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From: Taule Bretagne
Hi MATTEW,
Yesterday ,I was not sure ,that I got a true contact with A 12 grey conector .With a verified test ,circuit is open ........With FSM ,various procedures all conclusions , stil the same "open circuit "........My last firing test I had code C 12 --------that's all ................after no firing again ,,C 12 ,H 16 .
I was understanding to install new wire ,between ECM and ignition connector, but I am not pleased to cut wires ,As apparently ,it's seems to be the solution,I will do ,let you know later
Yesterday ,I was not sure ,that I got a true contact with A 12 grey conector .With a verified test ,circuit is open ........With FSM ,various procedures all conclusions , stil the same "open circuit "........My last firing test I had code C 12 --------that's all ................after no firing again ,,C 12 ,H 16 .
I was understanding to install new wire ,between ECM and ignition connector, but I am not pleased to cut wires ,As apparently ,it's seems to be the solution,I will do ,let you know later
Le Mans Master
Joined: Aug 2015
Posts: 6,119
Likes: 1,997
From: St. Charles MO
Hi MATTEW,
Yesterday ,I was not sure ,that I got a true contact with A 12 grey conector .With a verified test ,circuit is open ........With FSM ,various procedures all conclusions , stil the same "open circuit "........My last firing test I had code C 12 --------that's all ................after no firing again ,,C 12 ,H 16 .
I was understanding to install new wire ,between ECM and ignition connector, but I am not pleased to cut wires ,As apparently ,it's seems to be the solution,I will do ,let you know later
Yesterday ,I was not sure ,that I got a true contact with A 12 grey conector .With a verified test ,circuit is open ........With FSM ,various procedures all conclusions , stil the same "open circuit "........My last firing test I had code C 12 --------that's all ................after no firing again ,,C 12 ,H 16 .
I was understanding to install new wire ,between ECM and ignition connector, but I am not pleased to cut wires ,As apparently ,it's seems to be the solution,I will do ,let you know later
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Thread Starter
Intermediate
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From: Taule Bretagne
Hi followers ,
So I did intall a direct wire betwen ECM and ICM ,and I have cut wires ,only remove insulation ,and place a direct wire ,by only twisting around bare location ,but no success.maybe not thight enough ......will try again .I look to maximum threads ,concerning this probem ,and finally.,I found one with strictly my problems,I will take care of these advices ..So this thread tittle is ,"1992 LT1 no start due to short to IC circuit 423.How to find the short " .some news later.
So I did intall a direct wire betwen ECM and ICM ,and I have cut wires ,only remove insulation ,and place a direct wire ,by only twisting around bare location ,but no success.maybe not thight enough ......will try again .I look to maximum threads ,concerning this probem ,and finally.,I found one with strictly my problems,I will take care of these advices ..So this thread tittle is ,"1992 LT1 no start due to short to IC circuit 423.How to find the short " .some news later.