westtexasbuff

iTrader: (40)

I posted another thread in the PCM diagnostics section, but figured more people would view it here... Alright so I just finished up my build and had a friend come over to try to put in a new tune to try and fire it up, but we're getting a "unable to locate VCM" error in HP Tuners.

Things I've already checked/done.

- cig fuse good
- brand new battery
- checked all grounds
- obd2 port is getting power/ground
- pcm is getting power because pump primes when key on.

What could be the issue? Bad PCM? It's not HP Tuners drivers, or an issue with the cable because we hooked it up to my friends truck and it read his PCM just fine after we had issues with mine.

Sarg

iTrader: (6)

I got this when I did not have a good enough ground to the obd2 port. Maybe try hooking a scan tool to the port?

hardbodeez

iTrader: (10)

Power or ground problem to the connector.

dschmittie1

iTrader: (64)

You will need to check all your PCM power and grounds. Also ohm the data wire from the PCM to the DLC connector.

Also last year after relocating my fuse blocks under the dash and rewiring things I missed one of the grounds that connects at the bottum of the A pillar under the dash. and created a similar problem

WheelsUp84z

iTrader: (14)

Pin on the pcm connector came loose on mine that did the same thing. Blue connector pin 59. It was a new harness so I just think the pin wasnever seated all the way. I troubleshot for hours to find that.

pwrtrip75

iTrader: (8)

You dont have the scanner on also by chance do you? If the scanner is connected you wont be able to read or write with that program. I get that error when I forget to disconnect the scanner.

93BlackBeast

iTrader: (31)

Just to clarify, the scanner program can be on and still work it just has to be "disconnected" in the top left (little grey lightning bolt). But you're right...I've done this many times as I'll be logging and tuning and forget to disconnect from the scanner and get the error in the VCM editor.

westtexasbuff

iTrader: (40)

Thanks for the replies.... no the scanner was not on while we tried to pull the tune. I checked the obd2 port with a multimeter and it's getting good power/ground. I haven't checked the serial data wire though.

I used the tick performance battery relocation kit, and it comes with two grounds. I know one of them goes on the driver's side from the block to the chassis (which is the only one I have on right now), but where does the other go? I'm assuming passenger side block to chassis as well?

westtexasbuff

iTrader: (40)

Got all grounds fixed, now HPTuners cable lights up when before it didn't. Ohmd the data wire and its getting 3.5v. Is it supposed to see 5v, or is 3.5 sufficient? Thinking bad PCM. Anyone got any other ideas or suggestions?

Ryans99ls1

iTrader: (16)

just swap in someone elses pcm to see if you are right. other than that, seems like you are doing everything you can to trace it. have you tried using your hpt on someone elses car?

Gonoma

iTrader: (15)

Check the data pin inside the obd2 port...mine got worn out from plugging and unplugging and would check out fine with a meter but when the cable was plugged in it wouldn't get a good connection. So I took the pin out and pressed the tab back down so it would get a good connection and it has worked ever since...took days to finally figure it out and support on hptuners forum sucks do don't even bother