1993 LT1 Ignition problem
Thread Starter
Advanced
Joined: Jul 2011
Posts: 80
Likes: 0
Yes, I did disconnect ECM connector A when checking Voltage... My friend recommended the coil swap but I was wondering myself as to why and how this could affect the problem.. Plus it is a new Coil...
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
What have you done recently to the car before this started? Have you specifically done any work under the dash? I replaced the speedo in my 92 and when I put it all back together, I had a CCM data wire pinched between the steering column and bracket with voltage to ground. Drove me crazy for weeks.
Thread Starter
Advanced
Joined: Jul 2011
Posts: 80
Likes: 0
Interesting point, I had the steering wheel off some time back because of a blinker problem. I planned on replacing the Blinker switch but found the problem was actually a broken part/linkage preventing the blinker lever from actuating the switch. This could be a possibility and I am running out of ideas as to any other causes.. Thank You!
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Thread Starter
Advanced
Joined: Jul 2011
Posts: 80
Likes: 0
Yes, Its always been a strong running car, the only problem I've had has been restarting the engine once it warms up. I think I caused this by Gunking/washing the engine (like a fool) At first it developed a miss which later turned into difficulty starting after it warmed up. The miss went away. I assumed the Optispark was the problem, replaced that and ran fine but still would not restart when warm. replaced Coil, ICM now it does not want to start even cold. I did get it started once and ran fine for 5 minutes then crapped out again.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
What was the voltage reading on circuit 423? Assuming the test procedure was followed correctly, I would be surprised if the steering column problems are relevant to the issue since circuit 423 does not run inside the cabin.
My suggestion would be to run the voltage check again while a helper flexes the harness between the ICM and ECM, if you get a change in the reading the portion of the harness being moved should be inspected carefully for damaged wiring. good luck.
My suggestion would be to run the voltage check again while a helper flexes the harness between the ICM and ECM, if you get a change in the reading the portion of the harness being moved should be inspected carefully for damaged wiring. good luck.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
When searching for a circuit shorted to voltage, I would expect to see battery voltage (12 volts) or 5 volts which is the supply voltage sent to sensors by the ECM. Pay close attention to the spot where the harness transitions from the engine to the firewall, it is a common spot to have problems with chafing.
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
You may want to have the ICM tested or replaced again. I've gotten bad ones from the parts store for both my '85 and my '92. The '92 ICM and the way its mounted/cooled has issues with heat. There are several threads on this forum that talk about this issue and how to fix it, use the search to find them that's what I did. Good luck man! 
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
Also, really try to find the offending wire/short and wrap it up good otherwise it will likely rear its ugly head at a very inopportune time!
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
Find that shorted wire! I bet if you read out the codes, it will give you ECM or CCM serial data line errors...
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
What I did was this: I used a DVM to measure amperage by connecting one lead to a pin in the ALDL, and the other lead to chassis ground. Key on, car off I went through each pin until i found power to ground from the ALDL pinout. Mine was the brown serial line (CCM/ECM communications). Then I traced that wire everywhere through the dash until i found where it was pinched and found where the copper was exposed and shorting.
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
Yes it is. But I would be willing to bet that in your case (like mine) the answer is to start looking around the steering column since you were doing some work in that area. You shouldn't need to worry at this point with trying pull the CCM.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Was your code a DTC41 Module #4 or was it a 41 Module #1 ? If it is a DTC41 then this is a fault code for the ICM not receaving 4.5 volts. This is giving in the video, and should be tested on the car at both the ICM terminal, and the ECM terminal with a good Quility DVOM.
When you remove any of the connectors make sure the (pins) and (sockets) are absalutely clean and shiny, if there is any corrosion at all this could be a problem..
I would spend some time and go over all of your (Grounding) points, and make sure they are clean and tight.
When you remove any of the connectors make sure the (pins) and (sockets) are absalutely clean and shiny, if there is any corrosion at all this could be a problem..
I would spend some time and go over all of your (Grounding) points, and make sure they are clean and tight.