New member
Thread Starter
6th Gear
Joined: Oct 2020
Posts: 6
Likes: 0
New member
Hello Guys and Gals
am a new member from long Island NY
I have a 90 c4 I picked up. The person I bought it from was doing a conversion from automatic to manual. The car has the auto transmission attached to it, he changed the inside wiring harness to the manual one.its cold and I just want to get it running for the winter and in the summer I'll change the transmission.my question is on the automatic shifter theirs a connection but the harness has no plug fo it. I imagine it's the neutral safety switch. can I jump that to make it work?
am a new member from long Island NY
I have a 90 c4 I picked up. The person I bought it from was doing a conversion from automatic to manual. The car has the auto transmission attached to it, he changed the inside wiring harness to the manual one.its cold and I just want to get it running for the winter and in the summer I'll change the transmission.my question is on the automatic shifter theirs a connection but the harness has no plug fo it. I imagine it's the neutral safety switch. can I jump that to make it work?
Last edited by Jossey; Nov 4, 2020 at 03:13 PM.
Administrator
Joined: Mar 2001
Posts: 367,758
Likes: 24,681
From: In a parallel universe. Currently own 2014 Stingray Coupe.
C7 of the Year - Modified Finalist 2021
MO Events Coordinator
St. Jude Co-Organizer
St. Jude Donor '03 thru '25
NCM Sinkhole Donor
CI 5, 8 & 11 Veteran
Moved to C4 Tech.
Safety Car
Joined: May 2001
Posts: 4,741
Likes: 1,639
From: Fairfax Virginia
Hello Jossey,
Welcome to the wonderful World Of Corvettes and especially to the Corvette Forum!
Anytime you buy a project that has not been completed you are going to need good sources of information. One of the most important items for any C4 owner is having a set of the Factory Service Manuals. Having the set is essential to being able to fix your Corvette. The FSM's are printed by Helm Publishing for about $100 in print or for about $25 on the Rockauto or Ebay sights. Be absolutely sure to get the right year manual to work with your Corvette.
The second most important tool is a Fuel Pressure Gauge with an extension hose. The correct fuel pressure is critical in the performance of the C4's. If the fuel pressure is off then the Corvette will not run properly.
Having a good Multi-meter and knowing how to use it will be important in getting the Corvette working 100%. A scanner would be a really helpful tool if it works on OBD1 vehicles, Code readers are helpful but not quite a scanner. I have an old Snap On MT2500 which is 1980's technology and works great with my C4.
I might consult with a local transmission shop to see if they might know the answers. A quick phone call to a transmission shop would tell you right away what the hole is for on the tranny. Are the cables from the transmission that connect to the throttle body still there to tell the transmission "when to shift" still connected? I am sorry I am not remembering the proper name of cable from the transmission...
I have a 1988 C4 with the 700R4 Transmission your Corvette has. I love my automatic and it works well and gets me over 30 mpg on the highway.
The switch to a manual might be a lot more work that it turned out to be so the previous owner bailed out. There are plenty of experts on the manual Transmissions here on this Forum. It is not as simple a swap as if I took off my Muncie transmission and bolted up a automatic. I have a 1968 C3 with a four speed as well. If I am not mistaken the ECM program is different for the manual Corvettes versus the Automatics. This might require a new ECM to make the system work as a manual.
But you are in the right place to find out this information! Take a few minutes and fill out your profile on this Forum Sight. This will help keep people from asking you the same questions over and over. The more complete the better we can help you. It helps both of us get your Corvette issues re-solved.
Best Regards,
Chris
Just for your knowledge, the C4's like your Corvette use Oxygen sensors in the EFI system. There is 1 on my 1988 and it is likely the same on your. On an OBD1 vehicle the Oxygen sensors are REPLACED every 24 months or 50k miles. They might still work but that doesn't mean they are accurate enough for the fuel system. They are cheap, easy to install and make a HUGE difference in your Corvette's Economy and performance.
Welcome to the wonderful World Of Corvettes and especially to the Corvette Forum!
Anytime you buy a project that has not been completed you are going to need good sources of information. One of the most important items for any C4 owner is having a set of the Factory Service Manuals. Having the set is essential to being able to fix your Corvette. The FSM's are printed by Helm Publishing for about $100 in print or for about $25 on the Rockauto or Ebay sights. Be absolutely sure to get the right year manual to work with your Corvette.
The second most important tool is a Fuel Pressure Gauge with an extension hose. The correct fuel pressure is critical in the performance of the C4's. If the fuel pressure is off then the Corvette will not run properly.
Having a good Multi-meter and knowing how to use it will be important in getting the Corvette working 100%. A scanner would be a really helpful tool if it works on OBD1 vehicles, Code readers are helpful but not quite a scanner. I have an old Snap On MT2500 which is 1980's technology and works great with my C4.
I might consult with a local transmission shop to see if they might know the answers. A quick phone call to a transmission shop would tell you right away what the hole is for on the tranny. Are the cables from the transmission that connect to the throttle body still there to tell the transmission "when to shift" still connected? I am sorry I am not remembering the proper name of cable from the transmission...
I have a 1988 C4 with the 700R4 Transmission your Corvette has. I love my automatic and it works well and gets me over 30 mpg on the highway.
The switch to a manual might be a lot more work that it turned out to be so the previous owner bailed out. There are plenty of experts on the manual Transmissions here on this Forum. It is not as simple a swap as if I took off my Muncie transmission and bolted up a automatic. I have a 1968 C3 with a four speed as well. If I am not mistaken the ECM program is different for the manual Corvettes versus the Automatics. This might require a new ECM to make the system work as a manual.
But you are in the right place to find out this information! Take a few minutes and fill out your profile on this Forum Sight. This will help keep people from asking you the same questions over and over. The more complete the better we can help you. It helps both of us get your Corvette issues re-solved.
Best Regards,
Chris
Just for your knowledge, the C4's like your Corvette use Oxygen sensors in the EFI system. There is 1 on my 1988 and it is likely the same on your. On an OBD1 vehicle the Oxygen sensors are REPLACED every 24 months or 50k miles. They might still work but that doesn't mean they are accurate enough for the fuel system. They are cheap, easy to install and make a HUGE difference in your Corvette's Economy and performance.
Drifting
Joined: Apr 2020
Posts: 1,925
Likes: 610
From: Orange, CA
Best of luck, sounds like someone got too deep and then gave up, leaving all the heavy lifting to you. Definitely grab yourself a Factory Service Manual from RockAuto, they're only $20 and will tell you exactly what wire goes where and how to make all the computers happy so that the Corvette will run and drive.
