DTC 42, bad opti or ECM?
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,107
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From: RI
DTC 42, bad opti or ECM?
Driving it back from the shop from a tune and a new ECM was needed, my 93 just died on me in the middle of a busy intersection. Looking like a idiot, I pushed it into a parking lot where the car wouldn't start. Luckily after 5 minutes, it started up again and I was able to drive it back to the shop where DTC 42 was set. After shutting off, it wouldn't start at all. We tried an ICM from an LT1 impala and no luck, same symptoms. Opti is a MSD unit with less than 2000 miles on it. Service manual doesn't diagnose a bad distributor but faulty connections or faulty ECM. Could DTC 42 be a bad opti?
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
http://www.troublecodes.net/GM/92-93_57P.shtml
Nope not the opti
Grounded knock sensor drawing down the 5V from the ECM
Nope not the opti
Grounded knock sensor drawing down the 5V from the ECM
Last edited by Redeasysport; May 31, 2008 at 02:01 PM.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,107
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From: RI
are you referring to code 43 instead of 42?
42) The EST circuit voltage was below 0.5 volts when engine speed was below 3000 RPM.
43) One or both of the knock sensors were either open or grounded for 5 seconds.
42) The EST circuit voltage was below 0.5 volts when engine speed was below 3000 RPM.
43) One or both of the knock sensors were either open or grounded for 5 seconds.
Melting Slicks
Joined: Feb 2005
Posts: 2,135
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From: Sebastian Florida
St. Jude Donor '06
You might try to see if all the connectors are seated properly and check for broken wires at the harness. Seen more people break wires at the harness, because they pull on the wires w/harness.
Racer
Joined: Dec 2006
Posts: 292
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http://www.troublecodes.net/GM/92-93_57P.shtml
Nope not the opti
Grounded knock sensor drawing down the 5V from the ECM
Nope not the opti
Grounded knock sensor drawing down the 5V from the ECM
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,107
Likes: 0
From: RI
aside from that, the ICM works off of CKT 423 at the ECM and the knock sensors on CKT 496. How can one draw more power from the other and set off an opposite code. According to the service manual, DTC 43 will set if more than 4.1 volts is drawn from the knock sensors, not DTC 42.
