6.0l LS with TH400 kickdown wiring issue

[1990suburbanswap1]

Hello,


Ok, the engine is a 24x 6.0l LS and is attached to a TH400. The PCM was flashed to handle the TH400. I do have a wiring issue with it though. Vehicle is a 1990 2500 4x4 GMC Suburban. The original engine setup was a 350 with the TBI EFI. The single wire (orange) running from the TH400 runs up into a relay located in the engine compartment next to the old fuel pump relay. Out of the relay is two additional wires. A pink/black strip one which runs into the bulkhead and a tan/black strip one that went to the old ECM. I can't find any info on this wire but I'm assuming it was used to help control shifting and the kickdown during and after wide open throttle. I currently do not have the wire connected to anything. What do I need to do with this wire? Thank you for any help.

[Fast355]

Hello,


Ok, the engine is a 24x 6.0l LS and is attached to a TH400. The PCM was flashed to handle the TH400. I do have a wiring issue with it though. Vehicle is a 1990 2500 4x4 GMC Suburban. The original engine setup was a 350 with the TBI EFI. The single wire (orange) running from the TH400 runs up into a relay located in the engine compartment next to the old fuel pump relay. Out of the relay is two additional wires. A pink/black strip one which runs into the bulkhead and a tan/black strip one that went to the old ECM. I can't find any info on this wire but I'm assuming it was used to help control shifting and the kickdown during and after wide open throttle. I currently do not have the wire connected to anything. What do I need to do with this wire? Thank you for any help.

That is the Kickdown relay for your TH400. My 1987 G20 van 305/TH400 had the same setup. If you are DBC you can use an earlier gas pedal mounted switch. If it is DBW use a WOT window switch hooked to the 0-5v APS signal.

[1990suburbanswap1]

Hello,

Thank you for the help. Here is what I'm running. It is a DBW throttle system. It is stock for a 2005 Cadillac Escalade. The wire harness I purchased from PSI Conversions. The harness is setup for a 4l80e.
I'm not using it yet. The PCM has been flashed for the TH400. What would be a good model/brand for the window switch? What is The APS signal? I'm not familiar. What wire would that be? Is there anything else that I need to know? Thx again.

[Fast355]

Hello,

Thank you for the help. Here is what I'm running. It is a DBW throttle system. It is stock for a 2005 Cadillac Escalade. The wire harness I purchased from PSI Conversions. The harness is setup for a 4l80e.
I'm not using it yet. The PCM has been flashed for the TH400. What would be a good model/brand for the window switch? What is The APS signal? I'm not familiar. What wire would that be? Is there anything else that I need to know? Thx again.

APS stands for Accelerator Position Sensor aka the gas pedal. However I just glanced and the last TPS window switch I bought was $60. The cheapest one I could find today was $123. I think I would figure out a way to mount a micro switch to the gas pedal. I went with the window switch because it made it very easy to adjust when the kickdown circuit energized, I set it around 50% throttle.

https://www.summitracing.com/parts/nos-15640nos?seid=srese1&gclid=EAIaIQobChMI3p22rr_5-AIVw2xvBB0g_Q4kEAQYCSABEgIqSPD_BwE

[1990suburbanswap1]

Thank you again. I'll Look and see what is out there and give it a shot. Let u know what I come up with.