DTC 36 Troubleshooting ?
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,521
Likes: 4
From: Windham, NH
DTC 36 Troubleshooting ?
I have a 93 (w/LT1) that just started bucking badly. Service Engine Soon light is ON. I accessed the codes and came up with #36. I went to my trusty GM Service manual and on pages 6E3-A-70 and 6E3-A-71 it give me the diagnostic procedures. NO PROBLEM! I get thru the first 2 steps and get 4.75 Volts. I start to go thru the steps for "4 to 6 volts" and it wants me to "disconnect distributor connector.- Ign. ON.-Measure voltage on treminal A". I can't figure out where the hell the distributor connector is!! The wires I would THINK are the Distributor connector wires are considered to be the "Ignition System Test Connector" in the book. These are the wires that actually go down to the distributor. Am I taking the book too literalay or am I overlooking something else. I disconnected the 4 terminal comnnector on the Ignition Coil Module and checked the voltage on terminal "a" on thet and got 11.7 volts. HELP!!!!!!!!!!!!!!
Jim
P.S. I put a MSD Optispark Dist. on this car almost 2 years ago to try to correct a no run problem. It turned out to be the Ignition Control Module at fault.
Jim
P.S. I put a MSD Optispark Dist. on this car almost 2 years ago to try to correct a no run problem. It turned out to be the Ignition Control Module at fault.
Last edited by Jim Martley2; Jul 6, 2008 at 06:44 PM.
Safety Car
Joined: Oct 2007
Posts: 3,816
Likes: 0
From: :45 minutes from everywhere / E-I-E-I-O
First you test for proper voltage on terminal B of test connector.
If that's good (4 - 6 V), then you are testing to see if that same 4 - 6 V is getting to terminal B of the same wire AT THE DISTRIBUTOR.
If you have 11.7 volts, then somewhere between the test connector, and the distributor, extra voltage is 'gettin' in' somehow. The voltage is supposed to be 4 - 6 V again on the same B wire AT THE DISTRIBUTOR.
The distributor connector is the 4 wire connector on the passenger side going down to the opti. Be careful of the snap locking clip/tab that holds on the connector - they break easily. Use a coat hanger shaped into a hook, and get behind it just enough to pull away the lock tab, and use needle-nosers to gently work loose the connector. DON'T pull it out by the wires!!!
If that's good (4 - 6 V), then you are testing to see if that same 4 - 6 V is getting to terminal B of the same wire AT THE DISTRIBUTOR.
If you have 11.7 volts, then somewhere between the test connector, and the distributor, extra voltage is 'gettin' in' somehow. The voltage is supposed to be 4 - 6 V again on the same B wire AT THE DISTRIBUTOR.
The distributor connector is the 4 wire connector on the passenger side going down to the opti. Be careful of the snap locking clip/tab that holds on the connector - they break easily. Use a coat hanger shaped into a hook, and get behind it just enough to pull away the lock tab, and use needle-nosers to gently work loose the connector. DON'T pull it out by the wires!!!
Last edited by schrade; Jul 7, 2008 at 04:50 PM.
Advanced
Joined: Sep 2002
Posts: 74
Likes: 0
From: Niskayuna NY
Hi Jim,
I'm in your neighborhood Colonie
Opti sparks are a pain in the butt to diagnose ...I just did a replacement of an Msd
last week it didn't give me any codes but an h16 .I did replace the ICM and the coil with a Msd
Do you have the original plug wires .... I found a bad wire on mine
I'm in your neighborhood Colonie
Opti sparks are a pain in the butt to diagnose ...I just did a replacement of an Msd
last week it didn't give me any codes but an h16 .I did replace the ICM and the coil with a Msd
Do you have the original plug wires .... I found a bad wire on mine
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
Everything schrade said is right on the money. Just one thing to add that might make it easier. The FSM should identify the wire colors as well. Rather than unplug the connector use a sharp sewing needle to pierce the insulation and take your readings that way. NOT a pin or anything that could damage the insulation or wiring, but a sharp needle would work.
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,521
Likes: 4
From: Windham, NH
Thanks guys!!!
I just realized that with the MSD Opti there is NO seperate connection at the "distributor". The wiring is connected directly from the plug on the Intake Runner area straight into the Opti and the factory Opti had a "jumper harness" that connected the two. Thanks schrade for opening my eyes to this!!!!!
It sounds like the MSD Opti is dying so I ordered a "Delphi" replacment along with another water pump assm. I hope they are here before the weekend.
It just ticks me off that I went for the BIG bucks ($515. + "handling") when I bought the MSD unit, figuring that it would be the LAST Opti I would have to change on this car.
Thanks again!!!!!
I just realized that with the MSD Opti there is NO seperate connection at the "distributor". The wiring is connected directly from the plug on the Intake Runner area straight into the Opti and the factory Opti had a "jumper harness" that connected the two. Thanks schrade for opening my eyes to this!!!!!
It sounds like the MSD Opti is dying so I ordered a "Delphi" replacment along with another water pump assm. I hope they are here before the weekend.
It just ticks me off that I went for the BIG bucks ($515. + "handling") when I bought the MSD unit, figuring that it would be the LAST Opti I would have to change on this car.
Thanks again!!!!!
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Racer
Joined: Sep 2007
Posts: 393
Likes: 0
From: Bartonville Illinois
You need to have the distributor harness inspection plug unhooked when you do the voltage check. It is located between #4 and #6 injector on pass. side.
If the voltage is right there, then they want you to plug it back in and then remove the plug at the Opti and do the same test.
This is an open circuit test to check the wires and ECM. If you leave it all plugged in then you won't get the proper readings because of the load the opti puts on the circuit.
By the way if your new to this. My FSM has a mistake on that troubleshooting page for DTC36. You will be looking at signals from Lo Res to ground, Hi res to ground. I read about 4.7 volts on mine.
If the voltage is right there, then they want you to plug it back in and then remove the plug at the Opti and do the same test.
This is an open circuit test to check the wires and ECM. If you leave it all plugged in then you won't get the proper readings because of the load the opti puts on the circuit.
By the way if your new to this. My FSM has a mistake on that troubleshooting page for DTC36. You will be looking at signals from Lo Res to ground, Hi res to ground. I read about 4.7 volts on mine.
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,521
Likes: 4
From: Windham, NH
I bought the unit a little over 2 years ago thru Summit Racing. I put about 10,000 miles on the car since I installed it. MSD only warranties their products for 1 year.
Jim
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,521
Likes: 4
From: Windham, NH
I just posted pictures of what my MSD Opti looked like when I took it off last night. NOT pretty!!
http://forums.corvetteforum.com/show....php?t=2073658
http://forums.corvetteforum.com/show....php?t=2073658
Racer
Joined: Sep 2007
Posts: 393
Likes: 0
From: Bartonville Illinois
Thats real bad. The Opti I removed had some slop in the shaft, but not that bad.
It looks like the drive spline was not machined to be in the center of the distributor mounting holes and was putting constant side pressure on the bearing.
Bummer.
