Need Help with LTCC conversion on '94 Corvette
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 752
Likes: 28
From: Ottawa, Ontario
Need Help with LTCC conversion on '94 Corvette
We installed and connected a LTCC system in our '94 Corvette today; in accordance with Bob Bailey's instructions.
The LTCC system works fine, but now the ASR light is on and the in-dash tach is no longer working. The shop who did the connections (I did the fabrication and install myself) told me that that a signal (ground signal?) is still required from the ignition module for these two systems to function properly.
Has anyone had a similar problem and how do I fix it without running power and an EST signal back to the ignition module. I do not want to have any high voltage in the Opti-Spark........kind of defeats one of the purposes of the LTCC to save the optical side of the Opti-Spark.
The LTCC system works fine, but now the ASR light is on and the in-dash tach is no longer working. The shop who did the connections (I did the fabrication and install myself) told me that that a signal (ground signal?) is still required from the ignition module for these two systems to function properly.
Has anyone had a similar problem and how do I fix it without running power and an EST signal back to the ignition module. I do not want to have any high voltage in the Opti-Spark........kind of defeats one of the purposes of the LTCC to save the optical side of the Opti-Spark.
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
I have the LTCC setup on my 96 and I have had no problems with the tach. My ignition control module is not even installed anymore, so I know that's not required. As far as the ASR light, I can't comment, as my car didn't have ASR by the time the LTCC went on the car. However, it sounds like the shop doesn't know what they are talking about.
Pro
Joined: Feb 2001
Posts: 690
Likes: 1
From: Youngsville NC
I have the LTCC setup on my 96 and I have had no problems with the tach. My ignition control module is not even installed anymore, so I know that's not required. As far as the ASR light, I can't comment, as my car didn't have ASR by the time the LTCC went on the car. However, it sounds like the shop doesn't know what they are talking about.
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 752
Likes: 28
From: Ottawa, Ontario
Thanks for the comments. That is helpful.
I wonder if I having a grounding issue? I will have to look at that more closely.
This shop is REALLY REALLY good. They have solved several other electrical items on our car that would have driven other shops to the funny farm.
I wonder if I having a grounding issue? I will have to look at that more closely.
This shop is REALLY REALLY good. They have solved several other electrical items on our car that would have driven other shops to the funny farm.
Le Mans Master
Joined: May 2005
Posts: 7,336
Likes: 2,265
From: Central Maryland
If I recall correctly, the Delteq system required that you either bypass the stock tach filter or add an MSD tach amplifier in order to keep the tach working (I think this didn't apply to Model Year 1996, but I may be mistaken about this, and I can't recall what the reason was). It's possible that the same is true of the LTCC system.
Drop Andy Bogus a line. Seems to me he was running an LTCC setup on his LT1. He might have some useful insights to offer.
Live well,
SJW
Drop Andy Bogus a line. Seems to me he was running an LTCC setup on his LT1. He might have some useful insights to offer.
Live well,
SJW
Thread Starter
Burning Brakes
Joined: May 2008
Posts: 752
Likes: 28
From: Ottawa, Ontario
Well, with the help of Bob Bailey, we finally got the problem with tach signal sorted out.
Turns out the PCM is exactly the same (as in same part no.) for the '94 and '95 Vette, and the '95 takes a tach signal off of terminal A13 from the PCM. so Bob sent us a terminal and we wired from A13 to the wiring coming off of the tach filter for the I/P tach and ASR system.
Problem solved. Ignition control module and tach filter are now no longer being used and the engine is running great with the LTCC.
FINALLY!!
Turns out the PCM is exactly the same (as in same part no.) for the '94 and '95 Vette, and the '95 takes a tach signal off of terminal A13 from the PCM. so Bob sent us a terminal and we wired from A13 to the wiring coming off of the tach filter for the I/P tach and ASR system.
Problem solved. Ignition control module and tach filter are now no longer being used and the engine is running great with the LTCC.
FINALLY!!
