Transmission Codes, Limp Mode, And New PCM

Impact LJ

Impact LJ

TJ Enthusiast
Joined
Jul 21, 2020
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127
Location
Tampa, FL
Hi all,

2005 LJ Automatic - 140000 miles

On my way home from work, I noticed the Jeep was stuck in 2nd gear, limp mode. After getting the Jeep home, I check the codes and read the following:

P0700- Generic trans code
P1775-Solenoid switch valve
P0846- 2/4 pressure
P0888- Trans relay always off - Less than 3 volts to relay

Along with some other emissions codes.

Checked the fluid and it was at an adequate level while running on flat ground.

I am hoping the owner of Wrangler Fix can chime in if he believes the PCM/TCM could be at fault. Anyone else seen the same codes and solved the issue?
 
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@Wranglerfix

Wranglerfix.jpg
 
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Impact LJ said:
Hi all,

2005 LJ Automatic - 140000 miles

On my way home from work, I noticed the Jeep was stuck in 2nd gear, limp mode. After getting the Jeep home, I check the codes and read the following:

P0700- Generic trans code
P1775-Solenoid switch valve
P0846- 2/4 pressure
P0888- Trans relay always off - Less than 3 volts to relay

Along with some other emissions codes.

Checked the fluid and it was at an adequate level while running on flat ground.

I am hoping the owner of Wrangler Fix can chime in if he believes the PCM/TCM could be at fault. Anyone else seen the same codes and solved the issue?
Click to expand...
ive seen this happen. It was on a newer car but the same problem. What caused it was the tcm had no communication with the pcm. This can be anything from a broken wire to a bad tcm
 
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This sounds similar to the issue I just had (except for the P0888 code). Dropping the trans pan, swapping out the filter and putting in 6-7 quarts of fluid fixed it. Hopefully you find and fix the issue quickly.
 
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Jerry Bransford said:
@Wranglerfix

View attachment 211944
Click to expand...

Haha that's awesome, hopefully he can come to the rescue. I've checked out an old thread of your's on another forum a few years back about the 0775 code.

redneckpunk said:
This sounds similar to the issue I just had (except for the P0888 code). Dropping the trans pan, swapping out the filter and putting in 6-7 quarts of fluid fixed it. Hopefully you find and fix the issue quickly.
Click to expand...
Was your problem intermittent or did it happen every time you got in the jeep? It seems mine goes out of limp mode if I restart the Jeep.
 
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Bbrayden85 said:
ive seen this happen. It was on a newer car but the same problem. What caused it was the tcm had no communication with the pcm. This can be anything from a broken wire to a bad tcm
Click to expand...
I've never actually seen the PCM/TCM but it was my understanding that they were integrated into each other for the 2005 model year which is when issues started arise?
 
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Impact LJ said:
Was your problem intermittent or did it happen every time you got in the jeep? It seems mine goes out of limp mode if I restart the Jeep.
Click to expand...

Mine was all of the time, but it also sat for a few years and all of the contaminants settled to the bottom; basically clogged the filter. The process was fairly easy and not expensive. When I checked the fluid with the dipstick, it looked normal, but the stuff that came out of the filter was almost black. I could clear the codes and it would shift normally.
 
Does it have a new PCM or you're asking if you need to get a new one? A guy in my club is going through the same issue but he just put in a new PCM from wranglerfix and his LJ went right back into limp mode 2nd gear.
 
@Impact LJ It sounds like your pcm is failing from the 0846 and 0888 codes. The 0700 code is a generic one that says something is amuck on the transmission side of The Jeep.

Any erratic shifts or high transmission temperatures?

@joe98tj If the guy in your club is having an issue with one of my pcms please have him reach out to me.
 
Wranglerfix said:
@Impact LJ It sounds like your pcm is failing from the 0846 and 0888 codes. The 0700 code is a generic one that says something is amuck on the transmission side of The Jeep.

Any erratic shifts or high transmission temperatures?

@joe98tj If the guy in your club is having an issue with one of my pcms please have him reach out to me.
Click to expand...
I'll let him know but I don't think he's blaming the PCM.
 
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Wranglerfix said:
@Impact LJ It sounds like your pcm is failing from the 0846 and 0888 codes. The 0700 code is a generic one that says something is amuck on the transmission side of The Jeep.

Any erratic shifts or high transmission temperatures?

@joe98tj If the guy in your club is having an issue with one of my pcms please have him reach out to me.
Click to expand...
This is first issue I've had from the transmissions, all of a sudden I'm doing 45 miles an hour at 3k RPM and wondering what the heck is going on lol. That said I don't have a trans temp gauge but the jeep came with a secondary cooler in front of the radiator. never know what the guy before did...

Have you seen P1775 be attached to a PCM failure?
 
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Impact LJ said:
I've never actually seen the PCM/TCM but it was my understanding that they were integrated into each other for the 2005 model year which is when issues started arise?
Click to expand...
2005-06 were notorious for Chrysler pcm problems for several of their vehicles.

It was the first two years that Chrysler combined the ecm and tcm to form the pcm. The placement behind the battery and engine on the firewall was an engineering catastrophe.
Impact LJ said:
This is first issue I've had from the transmissions, all of a sudden I'm doing 45 miles an hour at 3k RPM and wondering what the heck is going on lol. That said I don't have a trans temp gauge but the jeep came with a secondary cooler in front of the radiator. never know what the guy before did...

Have you seen P1775 be attached to a PCM failure?
Click to expand...
The P1775 isn’t a “normal” code for a failing pcm.

How old is your battery?

Have you checked the LR pressure switch harness for shorts?
 
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Wranglerfix said:
2005-06 were notorious for Chrysler pcm problems for several of their vehicles.

It was the first two years that Chrysler combined the ecm and tcm to form the pcm. The placement behind the battery and engine on the firewall was an engineering catastrophe.

The P1775 isn’t a “normal” code for a failing pcm.

How old is your battery?

Have you checked the LR pressure switch harness for shorts?
Click to expand...
Battery is from 2018, unfortunately I'm away from the Jeep until the 29th. I did just do the valve cover gasket and the harness behind the cover may have been damaged in the process. Does the LR harness run back there? I'm not even sure what the LR harness is...
 
Today I disconnected the negative on the battery and got the only the codes P0508, P0633, and P0688.

After around a 10 mile drive I checked the coded again and got the same 3. Will keep updated with what codes come back as time passes.

Also noticed that there is a sticker that says "Remanufactured" and looks to be made by Cardone. Part No: 794528V — I called to see if they could provide information on when it was built to no avail.
 
So... several hundred miles later and the same 3 codes remain. One for the IAC circuit, one for the sentry key, and one for the PCM power relay.


A friend of a friend is a master mechanic for Chrysler. After reading my codes, he immediately mentioned that there may be a chafed wire near the back of the valve cover. Low and behold, I checked the wiring and sure enough I found a wire that was exposed.

Wrapped it up with electrical tape and after a wheeling trip yesterday the only sign of transmission issue are a slight delay and skipping noise when shifting into Drive which is intermittent.
 
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I am at my wits end !! The details 04 tj rubicon 4.0 42rle. Got into my jeep one morning and it was stuck in second gear. Replaced solinoid pack, filter , new fluid. Still stuck in second gear. Brand new aftermarket transmission, and new TCU. Still stuck in second gear. All connections correct no visible damage to wiring. I am lost, and don't know where to turn next.
 
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