dlwilson

iTrader: (1)

My PCM doesn't see TPS voltage at all in VCM Scanner, and it throws a P0122 Throttle/Pedal Position Sensor A Circuit Low. The engine won't run. The other codes are:
P0452 - Evaporative Emission System Pressure Sensor/Switch Low
P1637 - Generator L-Terminal Circuit

I have a 5.7 LS1 from a 2000 Corvette. I didn't get the TAC module or pedal with it, so I put on a DBC throttle body from a Camaro. I have a Chinese Amazon wiring harness. I'm using the original Corvette PCM service number 09354896 with red/blue connectors. LS1swap says that will PCM work with DBC: https://lt1swap.com/cable_conversion.htm I've put OS 12212156 on the PCM, and the only change to stock is to disable VATS. I've attached a HP Tuners bin file in case that's useful.

I've metered out the following pins in the harness, which matches the 2002 Camaro PCM pinout
TP Sensor Signal - Red 24
TP Sensor 5V - Blue 8
TP Sensor Ground - Blue 60

When I put a voltmeter across the 5V and Ground pins of the TPS connector I see 5V.
When I remove the Red connector from the PCM and put a voltmeter between Red 24 and Ground I see the TPS voltage go from 0.585 - 4.474V as I move the TPS. I've done this with two different TPSs.

When I scan with VCM Scanner I see 0.0V from the TPS.

In VCM Editor I see that System->General->Vehicle->Platform Type is F-Body and I see that
in the System->General->Vehicle->System Options table that ETC is set to 0 for F (and all other types).

I've also tried using another 09354896 PCM that I got from eBay, with no luck. I'm using PCM Hammer to write to the PCMs, since I don't want to pay to license them yet with HP Tuners.

The IAC works fine, and I can control it using VCM Scanner and hear it move in and out.

Every now and then I am able to get the engine to run by plugging/unplugging the TPS and IAC and MAF sensors in different combinations, but it doesn't last and there's no pattern to it.

I am out of ideas. Does anybody have suggestions? Not sure if I should be looking at software or hardware.

dlwilson

iTrader: (1)

I made a little progress. I started thinking that maybe one of the three pins in the Red/Blue connectors was damaged, so I drove back over to the garage, pulled the connectors off and inspected them and the PCM pins. Nope, they all look fine, but I did notice that my alligator clip giving power to the fuel pump relay had fallen off. I put it back on, and the fuel pump cycled and the car fired right up. So at least now I can bring it back to my home garage and look at it.

I'd still appreciate any suggestions about why I'm not seeing TPS voltage in VCM Scanner.