'93 no start - code 41. Please help!
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Pro
Joined: Jan 2004
Posts: 676
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From: Chester SC
St. Jude Donor '15-'16, '21,'24
'93 no start - code 41. Please help!
Finally home after being away for 3 weeks, I started the 93 Vette. She fired right up. 10 minutes later, the engine stopped as if it was out of gas. When I turned the key to restart I knew something was wrong. I hooked up Gordon Kilabrew's A-B jumper to the ALDL and code 41 was blinked. Pulled the ECM. Re-seated the PROM as well as the 4 ECM harnesses. Code 41 is still here and she still doesn't fire.
All suggestions are welcome.
Thanks from South Carolina ... watch the C6R's tomorrow at Brasulton, GA- Petit LeMans - ALMS
H Watkins
All suggestions are welcome.
Thanks from South Carolina ... watch the C6R's tomorrow at Brasulton, GA- Petit LeMans - ALMS
H Watkins
Pro
Joined: Jan 2005
Posts: 520
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From: Richmond Va
you should be jumping a to g on a 93, check out this link. http://www.c4guru.com/articles/CCMCodePull.pdf
Thread Starter
Pro
Joined: Jan 2004
Posts: 676
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From: Chester SC
St. Jude Donor '15-'16, '21,'24
clf93lt1:
Thanks for replying. I see now that the A to G jump is for the CCM diagnostics. A to B is the ECM trouble codes that I tried. Too late (and dark) now to try my A to G jump. Results will follow tomorrow.
Regards, HKW
Thanks for replying. I see now that the A to G jump is for the CCM diagnostics. A to B is the ECM trouble codes that I tried. Too late (and dark) now to try my A to G jump. Results will follow tomorrow.
Regards, HKW
Team Owner
Joined: Aug 2000
Posts: 40,156
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From: San Pedro CA
the A-G will open up the CCM, but the CCM will present the ECM codes in a much more readable manner.
Code 41 = knock sensor. Make sure the wires are good on them... they might fail... it's rare. However, code 41, from my memory, usually indicates something else is wrong. It would require a helm manual to figure out completely.
Code 41 = knock sensor. Make sure the wires are good on them... they might fail... it's rare. However, code 41, from my memory, usually indicates something else is wrong. It would require a helm manual to figure out completely.
Advanced
Joined: Sep 2007
Posts: 59
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From: Spring Hill Florida
Code 41 per my 1989 Helms, which may or may not be the same as your 93, but better than nothing at this point right!
Cylinder Select Error
faulty or incorrect mem-cal.
Check the mem-cal to be sure the the locking tabs are secure. Also check the pins are secure and making proper contact. It is also possible the ecm is faulty.
Just a summary from the book, I know nothing!
Cylinder Select Error
faulty or incorrect mem-cal.
Check the mem-cal to be sure the the locking tabs are secure. Also check the pins are secure and making proper contact. It is also possible the ecm is faulty.
Just a summary from the book, I know nothing!
Thread Starter
Pro
Joined: Jan 2004
Posts: 676
Likes: 196
From: Chester SC
St. Jude Donor '15-'16, '21,'24
93 No Start; Code 41
Thanks for all the replies.
I jumped A to G to read codes from the CCM. Code 41 was the only fault code to show up there, as well as when A to B was jumped. In my Helms manual, page 6E3-A-73 shows DTC 41 as :Ignition Control Circuit open or short. Troubleshooting first goes after checking for > 0.5 volts present on the B cavity of the Coil Module harness conector. I measured 11.79 VDC. Next is disconnect the ECM connector "A" and check for any voltage present. with ignition on. This appears to be the blk/red low resolution signal. If there is any voltage present, there is a "short to voltage in IC circuit. If no voltage, ECM is "Faulty".
I don't know where this connector "A" is, and I'm afraid to probe just anywhere with the DVM with the ignition "on". Help on this onre, please!
BTW, all fuses under hood and inside the Vette are good.
H Watkins
I jumped A to G to read codes from the CCM. Code 41 was the only fault code to show up there, as well as when A to B was jumped. In my Helms manual, page 6E3-A-73 shows DTC 41 as :Ignition Control Circuit open or short. Troubleshooting first goes after checking for > 0.5 volts present on the B cavity of the Coil Module harness conector. I measured 11.79 VDC. Next is disconnect the ECM connector "A" and check for any voltage present. with ignition on. This appears to be the blk/red low resolution signal. If there is any voltage present, there is a "short to voltage in IC circuit. If no voltage, ECM is "Faulty".
I don't know where this connector "A" is, and I'm afraid to probe just anywhere with the DVM with the ignition "on". Help on this onre, please!
BTW, all fuses under hood and inside the Vette are good.
H Watkins
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
Thanks for all the replies.
Troubleshooting first goes after checking for > 0.5 volts present on the B cavity of the Coil Module harness conector. I measured 11.79 VDC. Next is disconnect the ECM connector "A" and check for any voltage present. with ignition on. This appears to be the blk/red low resolution signal. If there is any voltage present, there is a "short to voltage in IC circuit. If no voltage, ECM is "Faulty".
I don't know where this connector "A" is, and I'm afraid to probe just anywhere with the DVM with the ignition "on". Help on this onre, please!
H Watkins
Troubleshooting first goes after checking for > 0.5 volts present on the B cavity of the Coil Module harness conector. I measured 11.79 VDC. Next is disconnect the ECM connector "A" and check for any voltage present. with ignition on. This appears to be the blk/red low resolution signal. If there is any voltage present, there is a "short to voltage in IC circuit. If no voltage, ECM is "Faulty".
I don't know where this connector "A" is, and I'm afraid to probe just anywhere with the DVM with the ignition "on". Help on this onre, please!
H Watkins
With a volt meter, Black probe to Black wire on ICM plug which is (ground) and red probe to Pin B white wire. Turn ignition on. Voltage should be less than .5 volts DC.
If voltage is more than .5 volts DC, you need to disconnect the Gray connector at the ECM and with ignition on you should read 0 volts. That would indicate the ECM is bad.
Note: There are two white wires on the ICM 4 pin connector harness.
With the ignition on you will measure around 12 volts on white wire Pin D. This wire comes from the 10amp coil fuse. The other white wire Pin B goes to the ECM Gray connector pin A12.
If everything checks out they say to place the meter on AC scale and crank the engine. The AC voltage should vary from 1 to 4 volts.
The signal you are measuriing is the square wave signal that pulses the coil.
Last edited by Hooked on Vettes; Oct 6, 2007 at 02:40 PM.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
If the cranking test passes. (Voltage changing from 1 to 4 volts AC)
and you did measure 12 volts from the coil fuse on the White Pin D wire
The ICM would be suspect.
If no voltage change on Pin B (signal coming from the PCM) with the ICM plug disconnected and the engine cranking could be a bad PCM.
If you had a scope, trouble shooting would be easy. You could look at the High res. and Low resolution signals coming from the Opti, into the PCM and then the output signal from the PCM to the ICM.
and you did measure 12 volts from the coil fuse on the White Pin D wire
The ICM would be suspect.
If no voltage change on Pin B (signal coming from the PCM) with the ICM plug disconnected and the engine cranking could be a bad PCM.
If you had a scope, trouble shooting would be easy. You could look at the High res. and Low resolution signals coming from the Opti, into the PCM and then the output signal from the PCM to the ICM.
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