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No throttle response in Reverse or Drive

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Old Feb 8, 2023 | 07:36 AM
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Default No throttle response in Reverse or Drive

I'm trying to help a guy out with a 2015 L83/8L90 swap in a 67 C10. The engine, transmission, wiring harness, computers (E92/T87) and tuning all came from swapsupply in Houston. The truck starts fine and engine will REV when you move the gas pedal while in P/N. If you put it in R or D, you get zero response from the throttle body. It is going into gear as the truck will move forward and backward, but it is at idle RPM. If you put it back in P/N the throttle body works with pedal movement. This has occurred with 2 different pedals. The ECM is not throwing any codes. I hooked my scanner up and while in P/N you can see the pedal % and the TB % move. When in any other gear, you can see the pedal % move, but the TB% doesn't change. Right after that I determined that the battery has a bad cell, so I can't do any more troubleshooting until I get a replacement. Any thoughts as to what's going on? TIA.

Rob
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Old Feb 12, 2023 | 02:37 PM
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Have you tried logging the pedal and throttle body and PN status bits when the error occurs?
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Old Feb 13, 2023 | 11:42 AM
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Originally Posted by aknovaman
Have you tried logging the pedal and throttle body and PN status bits when the error occurs?
Yes. Pedal and TB move when in P/N. Pedal % moves when in R/D, but TB doesn't move. I can command the TB to move in any transmission position. Another problem I'm having is that it won't let me read the ECM. The TCM reads just fine, but it times out when I try to read the ECM. May be a different issue, or might be the main problem.
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Old Feb 13, 2023 | 02:56 PM
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check continuity of both can buss wires between obd2 port and ecu. tan should be a short from port to trans then from other tan wire at trans to ecu. and ahain on tan with black stripe. signal goes from port to trans then up to ecu. note there are 4 can buss wires at tcm connector. essentially loops through tcm.

​​​​​​​pm me your phone if you need to discuss
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Old Feb 14, 2023 | 12:15 PM
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Originally Posted by aknovaman
check continuity of both can buss wires between obd2 port and ecu. tan should be a short from port to trans then from other tan wire at trans to ecu. and ahain on tan with black stripe. signal goes from port to trans then up to ecu. note there are 4 can buss wires at tcm connector. essentially loops through tcm.

pm me your phone if you need to discuss
Good info, thanks. I'm waiting on them to send me a new computer. Hopefully it will fix the problem. I'll touch bases with you after that.

Rob
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Old Feb 14, 2023 | 12:44 PM
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If the engine starts and rev's up it's highly unlikely it's the ecu. With what I can determine from your info, it sounds like the ECU is not getting trans gear selection info.
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Old Feb 28, 2023 | 08:04 AM
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Originally Posted by aknovaman
If the engine starts and rev's up it's highly unlikely it's the ecu. With what I can determine from your info, it sounds like the ECU is not getting trans gear selection info.
Tried another computer, same problem. All things are pointing to a wiring issue with EFI harness. We are supposed to be getting a new harness next week. Will follow up.
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Old Nov 25, 2023 | 01:53 PM
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Originally Posted by Hart_Rod
Tried another computer, same problem. All things are pointing to a wiring issue with EFI harness. We are supposed to be getting a new harness next week. Will follow up.
Any updates?
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Originally Posted by sams1
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