forgot to mention its a 98 tj with a 98 grand cherokee 5.9l, a 98 ram 1500 4x4 5.9 wiring harness and a 98 dakota 5.9 2wd computer
PCM issue with 5.9 conversion? What should I check?
- Thread starter lostintime
- Start date
OP
So I got a computer for my 98 tj 5.9l conversion. Runs great but coming up with codes p0463 ( fuel sender volts too high), P1762 ( Governor pressure sensor offset) and p1763 ( governor sensor too high).
I changed the whole fuel pump module ( because nipple on pressure regulator was leaking) so it is new. I changed the governor pressure sensor in trans as wanted to do a fluid change anyways. I know both sensors run the sensor ground at pcm and I checked and no resistance from either sensor wire to pcm. It starts in third unless I manually down shift it, then it shifts fine all through the gears and lock-up. My fuel gauge constantly goes to full and I know it isn't full.
Now my question is what do I check? I already disconnected the o2 sensors and the codes keep coming up. If it was the sensor ground circuit in the pcm wouldn`t it set other codes as map, iac, and all other sensors as they run the same ground? I don`t know if I should just buy another computer or what to check next
I changed the whole fuel pump module ( because nipple on pressure regulator was leaking) so it is new. I changed the governor pressure sensor in trans as wanted to do a fluid change anyways. I know both sensors run the sensor ground at pcm and I checked and no resistance from either sensor wire to pcm. It starts in third unless I manually down shift it, then it shifts fine all through the gears and lock-up. My fuel gauge constantly goes to full and I know it isn't full.
Now my question is what do I check? I already disconnected the o2 sensors and the codes keep coming up. If it was the sensor ground circuit in the pcm wouldn`t it set other codes as map, iac, and all other sensors as they run the same ground? I don`t know if I should just buy another computer or what to check next
Wish I could help more but it has been too long since I have played with the wiring. Hopefully @RangerRick will pop in and offer up his help.
Lets tackle these problems separately on a part basis individually.
First the transmission trouble codes on the 46RE or similar MOPAR:
P1762 is the code for your governor. It means the voltage is out of range of what is expected.
P1763 means High pressure and with these two codes I would replace a couple of parts, clean the pan and replace the ATF 4+ fluid to proper level. Your Jeep is in limp mode because the ECM is seeing the incorrect voltage and assumes pressures are off. Most likely caused by dirt, grit or some kind of contamination in the governor & sensor units.
If this is a used transmission that was sitting for a while, it is always possible contaminants in the pan or if there was an opening from the dip stick or cooler lines, something got stirred up and is causing this issue. Also these sensors can go bad sitting for a real long time in a removed & shelved part that you recently cleaned up and started using again. A very common problem when using a used transmission, especially from a salvage yard that may have been sitting for months or more before you buy it.
Take extra care to avoid breaking this tan opaque part shown in the image below, (Park-Neutral insulator) on the valve body assembly. If it is a used transmission, chances are this piece is EXTREMELY BRITTLE from heat over time:
Since I "borrowed" this Image from elsewhere: Credit goes to user name: beeker on dodgeforum who did an excellent mini writeup on what happened to his truck over there so that I didn't have to go into complete detail on it. All in the MOPAR family right?
Change the transmission filter and clean out the pan/magnet very well prior to re-installation. DO NOT USE RED SHOP TOWELS to do this cleaning job. They will leave lint everywhere and this will cause you more transmission problems down the road when those fibers get washed out of their places and find other places they shouldn't get into.
RR
First the transmission trouble codes on the 46RE or similar MOPAR:
P1762 is the code for your governor. It means the voltage is out of range of what is expected.
P1763 means High pressure and with these two codes I would replace a couple of parts, clean the pan and replace the ATF 4+ fluid to proper level. Your Jeep is in limp mode because the ECM is seeing the incorrect voltage and assumes pressures are off. Most likely caused by dirt, grit or some kind of contamination in the governor & sensor units.
If this is a used transmission that was sitting for a while, it is always possible contaminants in the pan or if there was an opening from the dip stick or cooler lines, something got stirred up and is causing this issue. Also these sensors can go bad sitting for a real long time in a removed & shelved part that you recently cleaned up and started using again. A very common problem when using a used transmission, especially from a salvage yard that may have been sitting for months or more before you buy it.
Take extra care to avoid breaking this tan opaque part shown in the image below, (Park-Neutral insulator) on the valve body assembly. If it is a used transmission, chances are this piece is EXTREMELY BRITTLE from heat over time:
Since I "borrowed" this Image from elsewhere: Credit goes to user name: beeker on dodgeforum who did an excellent mini writeup on what happened to his truck over there so that I didn't have to go into complete detail on it. All in the MOPAR family right?
Change the transmission filter and clean out the pan/magnet very well prior to re-installation. DO NOT USE RED SHOP TOWELS to do this cleaning job. They will leave lint everywhere and this will cause you more transmission problems down the road when those fibers get washed out of their places and find other places they shouldn't get into.
RR
Check your grounds from the engine block to the transmission. Add extra grounds if you want. On my 5.9 swap I ran a ground from battery to frame to block to trans and back to frame. Overkill? Maybe.
On my 03 Grand Cherokee with a 42RE I had some funky shifting and codes popping up. Added extra grounds, fixed it.
Easy and cheap to try.
Paul
On my 03 Grand Cherokee with a 42RE I had some funky shifting and codes popping up. Added extra grounds, fixed it.
Easy and cheap to try.
Paul
P0463 voltage too high.
This trouble code indicates that the voltage the ECM is seeing is higher than the level expected for the amount of fuel in the tank.
Several things can cause this error from a wiring problem to bad grounds to a worn out sensor in the fuel tank sender assembly. It is usually not related to the fuel pump motor itself but more related to the rheostat that is related to fuel level in the tank. The float, the arm, the variable resistor and it's related contacts in most instances. If your gauge is reading erroneously or the fuel light comes on at random, chances are the wiper or rheostat portion is worn out or has a bad spot. This will directly correlate to bad grounds as well since almost all automotive circuits are working against ground which is the body chassis and is assumed to be a good connection. If there is a problem with the grounds to that sensor or where the ECM references its signals to ground, you can get all kinds of errors as Paul indicates a bad ground strap to the motor or wiring harness ground with even the slightest resistance like not having been soldered and gets corroded can cause trouble with the ECM recognizing good signals from bad.
Since this is a partially custom wiring job to make the V8 fit in your TJ Wrangler, pay close attention to the fuel sender circuit and it's related power/ground circuit wiring.
Expect a few of these types of things when any major engine swap DIY project is completed because it's very easy to overlook something minor that causes a MIL lamp on the dash. If it were easy to do, everybody would be swapping motors on a more regular basis.
RR
This trouble code indicates that the voltage the ECM is seeing is higher than the level expected for the amount of fuel in the tank.
Several things can cause this error from a wiring problem to bad grounds to a worn out sensor in the fuel tank sender assembly. It is usually not related to the fuel pump motor itself but more related to the rheostat that is related to fuel level in the tank. The float, the arm, the variable resistor and it's related contacts in most instances. If your gauge is reading erroneously or the fuel light comes on at random, chances are the wiper or rheostat portion is worn out or has a bad spot. This will directly correlate to bad grounds as well since almost all automotive circuits are working against ground which is the body chassis and is assumed to be a good connection. If there is a problem with the grounds to that sensor or where the ECM references its signals to ground, you can get all kinds of errors as Paul indicates a bad ground strap to the motor or wiring harness ground with even the slightest resistance like not having been soldered and gets corroded can cause trouble with the ECM recognizing good signals from bad.
Since this is a partially custom wiring job to make the V8 fit in your TJ Wrangler, pay close attention to the fuel sender circuit and it's related power/ground circuit wiring.
Expect a few of these types of things when any major engine swap DIY project is completed because it's very easy to overlook something minor that causes a MIL lamp on the dash. If it were easy to do, everybody would be swapping motors on a more regular basis.
RR
I have gone 'ground happy' ever since the transmission in my GC straightened out after adding the new ground from the block to the trans. Now I add grounds to everything that has a sensor in it. Throttle body, intake, heads, even the exhaust.
Most of these sensors operate off the 5 volt side of the pcm. It does not take much corrosion to effect these low voltage circuits.
Paul
Most of these sensors operate off the 5 volt side of the pcm. It does not take much corrosion to effect these low voltage circuits.
Paul
OP
I already changed the governor sensor, filter and oil.
That is what I will do next. Thanks Paul
OP
Well after installing grounds and pulling the wire harness out again and checked everything over I ordered a rebuilt ecm. Hope this finally fixes my problems( I`m pretty sure it will)