LS1 GTO ecm rev lock out

[slofut]

My 04 gto ecm, afaik pin 44 green connector, goes to ground at low speed or stopped, to energize the lock out solenoid. I'm getting 6k ohms on the ground side with ign on and 12vcd on the other side of the solenoid. Doesn't seem to be close enough to ground to work. Original solenoid seemed stuck when I pulled it out but a few operations on the bench with a battery and it free'd up. I replaced it with new anyway. Any ideas? I don't need it to be the ecm, it's been flashed to work in my 71 vette and everything else works great. But it is an 04 gto motor/ecm. Is 6k ohms normal for the ground output on this pin?

Any help would be appreciated.

[Hotwire]

Sounds like you burned up a driver (transistor) in the ECM unfortunately.

Are you seeing any transition from floating to 6k when you get the car over 6 mph? If so it might have enough left in it to operate a relay since a coil doesn't take a lot of current to operate. If not, might have to send it off and get the driver replaced. Or if you know someone with a good amount of electronics experience and is handy with a soldering iron, you could possibly get a cheap ecm from a pull a part yard and just swap parts out once you sniff out the correct driver to replace.

[slofut]

Thank you Jeff, I suspect you're exactly right. Did some troubleshooting yesterday and the pcm is just not outputting ground, in fact it's intermittent between 6k and 10k. As long as there isn't another input required that I don't know about, it''s prob the driver or related components. I'll pull the board today and see if I can determine which transistor does this and maybe replace some electrolytics while I'm in there. So with the pcm plugged into the car and powered on there should be ground at pin 44, as the car would be stationary. But wait, if the VSS wasn't wired correctly that could prevent the pcm seeing the correct speed or zero mph correct? Maybe there's one more possibility. Thanks so much for your response Jeff, appreciate the help.
Bill

[slofut]

Also, vss is just dry pulses? I see a low and high is that ref to ground? I think just open or closed. I'll look further. Keep in mind this is an 04 gto transplant in my 71 vette so that's why all the questions.

Another possibility... I had the pcm flashed by Tom Bauer Racing for stand alone, is it possible to program this function (rev lockout) out in programming? I asked Tom but he said he hasn't "messed with rev lockouts" so he doesn't know (his words) He's a great guy btw... and answers txts and call quickly and even five years later.

[slofut]

Vss is an ac generator, low and hi side, connected correctly to my pcm but with different wire colors than the diagram. Expedite plan now is install a lighter spring in the solenoid to buy time. I'll get another pcm and have it flashed then fix this one for a spare later. Ultimately I want to retain the factory rev lock out.

[Hotwire]

Do you know if the GTO ecm is auto or stick to begin with? Is the correct segment swapped in for the manual trans?

VSS sensor is a hall effect sensor, just a coil at the end of the sensor, when the metal teeth of the tone ring go by the sensor it changes the coil's inductance, creates a small voltage spike that the ECM reads. The wires from the VSS to ECM should be twisted pair to eliminate any noise from the signal. (green and purple if I remember right) The circuit is floating, referencing itself inside the ECM, either wire should not be grounded, sensor is also floating.

https://ampdistributing.com/collecti...ing-rotor-gear

Keep a probe on the ECM lockout wire and get the car over 6 mph to see if the state of the pin changes?

Be aware, most ECMs I've worked on have a clear varnish/conformal coating on it, sometimes it's a pain to clean off and solder to.

[slofut]

Jeff I can only suspect that it's a manual ecm, the motor is documented 04 gto/manual flywheel and the ecm and manual trans wiring harness was with it, although the trans had been swapped for a firebird t56. The ecm part number comes up as up as 04 gto but its from a local salvage yard so anything is possible. There is a nice tuning shop here, if they have hp tuners or similar would they be able to see that programming and identify the ecm?

[Hotwire]

Yes anyone with hptuners can make a copy of your tune and look to see what segment is installed in the ECM. Kind of seems like the lockout pin is floating, only reason I'm asking. If it's not the tune then it's unfortunately seems like the ECM needs some work.

When you're probing, are you at the wire or the ECM? Could the harness have gotten knicked at some point? Only reason I'm asking if you see a change when you bring it up to speed, could be a bad wire? Can you get to the ECM connector and do a continuity check on the wire itself?

Sorry to be throwing you all over the place, just hard to diagnose through a keyboard..

[slofut]

Yes anyone with hptuners can make a copy of your tune and look to see what segment is installed in the ECM. Kind of seems like the lockout pin is floating, only reason I'm asking. If it's not the tune then it's unfortunately seems like the ECM needs some work.

When you're probing, are you at the wire or the ECM? Could the harness have gotten knicked at some point? Only reason I'm asking if you see a change when you bring it up to speed, could be a bad wire? Can you get to the ECM connector and do a continuity check on the wire itself?

Sorry to be throwing you all over the place, just hard to diagnose through a keyboard..

Not at all Jeff, I appreciate the help. Yes I have easy access to the ecm and have checked the wire on pin44 at the ecm and at the plug with the solenoid unplugged. I am however, assuming the pin should be at ground with the ignition on and the car stationary. Thinking the solenoid would have to be energized with the car stopped to be able to get reverse. I have the car on the lift so I can get under and also access the ecm through the gill opening. So I shouldn't necessarily have to have the car rolling, correct? Also does bring up my earlier point abt the vss, if it's malfunctioning it could be reading over 5mph while at rest? Yes, seems the pin is floating at this point, and I see your point now that if I could get over 5mph it would tell me whether pin 44 is cycling at all. May have to do that. I think I'd like to check this tune, I'm beginning to suspect it's programmed out.

[slofut]

Just to follow up. So my ecm ended up (prob) being from an auto car, previous programmer went through and clicked off and on bits for manual trans etc... but the OS didn't know what to do with those selections. Had to find and dl a manual trans car OS, modify as needed for stand alone and manual trans and re-dl, pin44 ground output works now and original solenoid is working.
Thanks much for your help Jeff.

[Hotwire]

Hell yea! Glad to hear there was a resolution! Enjoy the the swap man!

[slofut]

Well, now I have another issue. The car now runs like it has a two barrel carb on it. All that massive load of torque is gone, I'm truly disappointed, it's not the same car, it backfires a lot more on overrun too (side pipes). The local guy is a tuner with two dynos, since nothing at all was changed exe the computer programming are my chances good that he can make it run as well as before? If it has to go on the dyno it's gonna cost me $450 but I was thinking about doing that anyway, but I just spent $300 getting the lockout working. Idk enough about ecu programming to know what to expect.

[Vimes]

Well, now I have another issue. The car now runs like it has a two barrel carb on it. All that massive load of torque is gone, I'm truly disappointed, it's not the same car, it backfires a lot more on overrun too (side pipes). The local guy is a tuner with two dynos, since nothing at all was changed exe the computer programming are my chances good that he can make it run as well as before? If it has to go on the dyno it's gonna cost me $450 but I was thinking about doing that anyway, but I just spent $300 getting the lockout working. Idk enough about ecu programming to know what to expect.

It sounds like when they fixed your manual trans issue, they did so by flashing the engine program from the manual donor too, rather than put your original engine tune in with the manual trans. I would not wait to get it onto a dyno tune, and would not drive it at all until it does get tuned. If the new program is far enough out, you could be doing hard damage to your engine.

If the same guy with the dyno fixed the manual trans problem, I'd speak to him about how he made the fix. If he didn't put your original engine parameters in on the manual trans, then he fixed one thing by breaking something else, and he either needs to put the original engine parameters back in with the new manual trans parameters, or give you a discount on a dyno tune.

[slofut]

Thank you Vimes, yea he put in a standard street tune. It honestly feels like a hundred horsepower difference. I'm running two O2 sensors, it may me looking for four, etc... Supposed to get with him this week to get it on the dyno.

[Hotwire]

As Vimes said, it's on the tuner that made the trans change.

If your previous tuned worked with no question and you weren't looking for a dyno tune I would get it dumped back in.

If the tuner has any idea what he's doing he kept your initial tune saved. I would tell him to reinstall the tune as it was and make the trans change as you requested. You paid for a service and did not get what you paid for.