99 PCM replace/update
#136
CF Veteran
This is way to complicated. Im thinking an issue with the cam sensor or that during the engine change, something isn't compatible. Were there different setups in '99? Did he get the 2000 version of something mixed in with 99..
#137
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From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
My jeep is a 99, I unbolted everything and put it on a rebuilt 92 block/7120 head. The only not stock parts are gaskets and header. Otherwise it's a standard factory 4.0 system unmodified.
#140
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From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Because there could be an issue with the wiring which needs to be ruled out. IMO I don't believe the flexplate is bent. How could that happen out of the blue?
However, I could see there still being a flexplate issue if there were 2 different causes for 1391 (one you inadvertently fixed while doing the engine change, and a new issue after the engine change)(it'd be about the same chance of it starting to rain blood in the next 5 minutes, but theoretically still possible).
That said, we're really starting to reach here, so let's get back to the wires. Hall sensors should be reading 0.0 or 5.0 volts. There is an acceptable range for power, but zero should be zero. However, you have some residual voltage there:
562023]
Does your meter autozero?
You should do this test on the camshaft sensor as well. We shouldn't get tunnel visual and keep thinking crank sensor.
IMO isolating the circuits as much as impossible is a worthwhile direction because cam and crank sensors share a TON of other grounds, and the issue could be in there someplace else:
Searching the harnesses along the K167 circuit for issues might not be a bad idea.
Anyway, rewire the 2 sensors, make sure the multimeter is zeroed, repeat the test for both of them and see if you can get 0.0.
If you still get residual voltage then put those new wires on the PCM ground (should be A4) and take everything else off.
However, I could see there still being a flexplate issue if there were 2 different causes for 1391 (one you inadvertently fixed while doing the engine change, and a new issue after the engine change)(it'd be about the same chance of it starting to rain blood in the next 5 minutes, but theoretically still possible).
That said, we're really starting to reach here, so let's get back to the wires. Hall sensors should be reading 0.0 or 5.0 volts. There is an acceptable range for power, but zero should be zero. However, you have some residual voltage there:
562023]
Does your meter autozero?
You should do this test on the camshaft sensor as well. We shouldn't get tunnel visual and keep thinking crank sensor.
IMO isolating the circuits as much as impossible is a worthwhile direction because cam and crank sensors share a TON of other grounds, and the issue could be in there someplace else:
Searching the harnesses along the K167 circuit for issues might not be a bad idea.
Anyway, rewire the 2 sensors, make sure the multimeter is zeroed, repeat the test for both of them and see if you can get 0.0.
If you still get residual voltage then put those new wires on the PCM ground (should be A4) and take everything else off.
Put new wires on the ground/ take everything else off, please specify a bit, I'm happy to try. Just not fully visioning your request.
#141
CF Veteran
Correct. You could check the ohms of the wires but if the sensors are good and the PCM is good I'd go ahead and put in entirely new devoted wires. Cut out the old wires completely.
Any chance of getting a scope?
Any chance of getting a scope?
#143
CF Veteran
If codes persist then K167 circuit includes 8 other sensors and wiring in some very vulnerable positions. See what A4 has for voltage.
BTW did you test the cam sensor? 1391 doesn't differentiate between the two.
BTW did you test the cam sensor? 1391 doesn't differentiate between the two.
#145
CF Veteran
BTW just change the signal wires for now. The power's probably OK and isolating the grounds is going to take some creative thinking.
#146
CF Veteran
Like:
See if A4 has voltage. Take the new cam and crank ground wires and connect to A4 such that the only grounds on A4 are the camshaft and crankshaft sensor grounds. Check the A4 voltage again. Clear codes. Crank twice (doesn't matter if it don't start cause 1391 will appear in cranking mode if present). See what codes you have.
I think that would work but we need to fully vet that out.
See if A4 has voltage. Take the new cam and crank ground wires and connect to A4 such that the only grounds on A4 are the camshaft and crankshaft sensor grounds. Check the A4 voltage again. Clear codes. Crank twice (doesn't matter if it don't start cause 1391 will appear in cranking mode if present). See what codes you have.
I think that would work but we need to fully vet that out.
#147
CF Veteran
Or alternatively, just give CMP and CKP their own dedicated ground on the block.
That approach seems to be Pathfinder tho.
That approach seems to be Pathfinder tho.
#148
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
how did you go checking the female harness pins for loose ?
did you clear all codes with a reader ?
If your truck is running fine, the chances of a bad wires are low imo
I am of the belief you will have symptoms if PCM earths are affected, not just codes.
did read a thread where a guy ran earth wire to PCM, due to a failure, his truck would not run.
This would suggest PCM earth is same as -ve, so an ohmeter between PCM earth and body should show a very low resistance (if this is correct)
You said you "thought" you may have a miss...either you do, or dont..how does it manifest itself?
access to a scope is probably needed to further diagnose the situation imo
as the flywheel is one of the few common parts, I once again suggest checking its runout
did you clear all codes with a reader ?
If your truck is running fine, the chances of a bad wires are low imo
I am of the belief you will have symptoms if PCM earths are affected, not just codes.
did read a thread where a guy ran earth wire to PCM, due to a failure, his truck would not run.
This would suggest PCM earth is same as -ve, so an ohmeter between PCM earth and body should show a very low resistance (if this is correct)
You said you "thought" you may have a miss...either you do, or dont..how does it manifest itself?
access to a scope is probably needed to further diagnose the situation imo
as the flywheel is one of the few common parts, I once again suggest checking its runout