Gen 3 REVERSE LOCKOUT HELP!!!!

terrybrown95919

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Ok, I know this has been discussed a bit in the past BUT here's the lowdown:

First noticed an engine light after the second auto car wash I tried. Not sure if it had anything to do with the problem. '04 Viper about 20K miles always garaged. Engine missed a couple times on the way home but was fine after that. I am the second or third owner. I think the car is mostly stock with the exception of a Corsa exhaust and a BBK throttle body.

Next day or two noticed I had to muscle up to get the car in reverse. Checked all the fuses which were fine. Bought a scanner and ran a system test. Results: "A short or open reverse gear solenoid." After 2-3 weeks got a new solenoid from Dodge and put it in. Did not fix the problem. Still need Popeye to get it in reverse. Wires are all like-new.

Any idea on what direction I should go next? Previous threads didn't provide much help. Next step, if I can't find the issue, is off to the local garage. Not sure they are much ahead of me on the learning curve.

Help!!
 

TexasViper35

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I don’t have a direct answer for you, just my very personal experience with this thing. But it may be insightful.

A rodent chewed the wires on mine, so I would drop the front part of the belly and look at the wiring carefully for any damage. Also, there is a fuse to an O2 sensor that is also linked to the Lock-Out, so double check that fuse, especially if you’ve done work (installed the new solenoid) because it could have popped.

ETA If you turn your key on and off three times and stop at On with the 3rd turn any fault codes will be displayed on the dash. Backfires are often caused by bad spark wires.
 
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terrybrown95919

terrybrown95919

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Ok here is the latest report:

1. Works great with the solenoid removed.
2. Red solenoid wire (@ solenoid) reads 11.5V DC key on or off
3. Black wire doesn't show connect to ground with key on or off.
4. Wires look fine. Harness is place.
5. O2 fuse good.

Did show code P0801 which was cleared

NEXT:?????
 
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terrybrown95919

terrybrown95919

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Hey Guys/Gals still looking for a possible solution............

1. Anyone run the Tremec without the Reverse Gear Lockout Solenoid installed?

Any other ideas? Bad PCM? Help!!

Thanks
 

Old School

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From the service manual:

When vehicle speed is less than 3 mph, the PCM
provides a ground for the solenoid (energized) and
allows shifting. When vehicle speed is greater than 3
mph, the solenoid is deactivated and prevents the
transmission from being shifted into reverse.
 

MoparMap

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I had this one happen to me, but in a much more obvious way. My speedometer was going crazy at a standstill and swinging the needle all over the place. Wouldn't let the car go into reverse because it thought it was moving. Fairly sure this isn't your problem as it would be more obvious, but it first happened to me on the way home from work in some pouring rain. I pulled connectors at the ABS module and the PCM to check and see if there was any corrosion on the pins. Both looked perfect and when I plugged it all back in everything worked just fine again (at least for the one test start I did). Could have also just been that I disconnected the battery and reset things, hard to say.

That being said, as Old School said, the PCM provides the ground for the circuit. Not 100% sure if the car needs to be running or if key on is enough to do it. It would be a transistor style ground though, which doesn't always register as a ground all that well on meters. They tend to want to see a load, so another thing you can try is putting a light bulb in where the solenoid would go. Since the 12v is there it sounds like your fuse is okay at least. The ground part not working points to either a bad wire or a PCM problem, though it's still a pretty vague problem. Could be a speed sensor issue or a PCM fault like the driver for the circuit blowing out. Hopefully just a wire problem though. I think they build those circuit drivers to shut off if they see excess current so they don't burn out.
 
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terrybrown95919

terrybrown95919

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Thanks, I did the disconnect, check, **** out, etc on some of the connectors but not from the PCM I think. Hopefully they won't be too difficult to get to. I appreciate all the input!!
 
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terrybrown95919

terrybrown95919

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ok, gonna have to expose my ignorance .... not quite sure how/where to do that. I pulled the pcm and disconnected the 3 connectors but not sure if I need to test the connector wire or the pcm output terminal??
 

Old School

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Unplug both the PCM and the solenoid. Set you meter to ohms, measure between the wire and chassis ground, should be infinite.
 

Chad Spackman

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It’s not a short to gnd. That would energize the solenoid and allow reverse. I don’t think you have proven it’s the pcm (yet). You should check the solenoid signal wire for an open. Which again means setting your meter to ohms. Car off off… Connectors disconnected at pcm and solenoid. One probe on the harness connector that goes to solenoid, the other probe on the harness connector that goes to pcm. If the wire is good end to end, your meter will read low ohms. If that reads correctly, and everything else you have stated is correct, it points to pcm. Which would not be good enough for me to go buy a pcm. There are further tests to prove definitively that it’s the pcm.
 

Old School

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It’s not a short to gnd. That would energize the solenoid and allow reverse. I don’t think you have proven it’s the pcm (yet). You should check the solenoid signal wire for an open. Which again means setting your meter to ohms. Car off off… Connectors disconnected at pcm and solenoid. One probe on the harness connector that goes to solenoid, the other probe on the harness connector that goes to pcm. If the wire is good end to end, your meter will read low ohms. If that reads correctly, and everything else you have stated is correct, it points to pcm. Which would not be good enough for me to go buy a pcm. There are further tests to prove definitively that it’s the pcm.
This is correct, a short would not cause the issue, an open would.
 
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terrybrown95919

terrybrown95919

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Ok Folks HERE IS THE RESULT:

After going through the various suggestions of the many helpful members, I got down to the last possible cause (I think, may have missed one or two). I ordered and replaced the PCM/ECM with a remanufactured unit. Surprisingly, it did correct the problem and the Lockout works as advertised!!

Thanks for all the help. I can back off on the weightlifting now as it doesn't take two arms to shift into reverse.

Best! Happy cruising.
 

MoparMap

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Glad to hear you got it fixed, though ***** it took a whole PCM to get there. Kind of feels like using a cannon to **** a fly. You might hold on to the old one either way. Someone might be able to repair it. Wonder if some code got corrupted or if the driver for the circuit just gave out.
 

BadAzp

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Dan Lesser has a business in Florida that fixes pcm's.
Cant think of the name off hand but someone here or on vtcoa or one of the fb pages will know .
 
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terrybrown95919

terrybrown95919

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I gotta believe that the car wash (mentioned in the first post) might have shorted the PCM out. I do have an '08 oem hood on that has those large intakes over the front portion of the engine. The replacement PCM came from Flagship One out of NY.

I think Dan may be building a home quite near my place.
 

Viper Specialty

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I gotta believe that the car wash (mentioned in the first post) might have shorted the PCM out. I do have an '08 oem hood on that has those large intakes over the front portion of the engine. The replacement PCM came from Flagship One out of NY.

I think Dan may be building a home quite near my place.

Not only am I building that monstrosity around the corner from you... but I live in Port Charlotte, have your phone number in my phone, had those control modules on the shelf, and the diagnostic equipment needed to troubleshoot it in about 5 minutes LOL.

OOOPS.

You are lucky you actually got that module from FS1. They are one of the shadiest module companies out there.
 

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