1999 Jeep Grand Cherokee Limited. 4.7 v8. 240000 miles+. Jeep started missing towing a light trailer up a grade, engine was heating but not to redline. Stopped and shut off then could not get a restart. Fuel pump runs and has pressure at the fuel rail. Cranks but sounds to be loading. Fault code indicates Cam Position Sensor P3040. I replaced the sensor and confirmed 5v power at the connector as well as a good ground and no shorts indicated. Secondary problem not likely related is failed harness in the drivers door. Any help???
No start condition. Cam Position Sensor indicated.
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Is the PCM connector in the engine compartment, passenger side, next to the firewall? I cannot get it apart to check if that is the correct connection. Removed red lock tab and tried everything but breaking it. Once open, which pins correspond to the cam sensor wires, I do not have the wiring diagram. Also, is there any chance that the Crank Position Sensor may be involved even though it is not throwing that code? Code shown consistently is P0340.
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The PCM has 3 connectors on it. It sits in the engine bay on the aft bulkhead close to the right fender (as seen from drivers position).
Disconnect negative battery terminal before removing any PCM connector.
Some googling showed that a bad battery or even a bad starter can cause this fault code to pop up. How is the batt voltage? Do you have a charger to charge it completely?
Disconnect negative battery terminal before removing any PCM connector.
Some googling showed that a bad battery or even a bad starter can cause this fault code to pop up. How is the batt voltage? Do you have a charger to charge it completely?
Wires from the PCM check out OK. Still getting JUST the cam sensor fault. Thinking about trying another sensor just in case it was bad out of the box (stranger things have happened). What might be my next move? I really can not afford to replace the ECM without knowing that is the problem. Anyone have ANY other thoughts? I am going into my second day of missing work now.
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Sometimes non OEM sensors can cause problems, but wonder if it would be the case here. There should be a possibility to measure the cam sensor, just google this first.
Crank sensor would give the same problem, but since you don't have any code from that one, i would not suspect it. Does the tachometer show rotation when trying to start? If yes, then the crank sensor should be ok.
Crank sensor would give the same problem, but since you don't have any code from that one, i would not suspect it. Does the tachometer show rotation when trying to start? If yes, then the crank sensor should be ok.
Tried new crank sensor. No luck. Same no start condition, still throws a cam position sensor fault. Going to try another cam sensor in the off chance that the first one was bad out of the box. Don't know where to go after that.
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If the second cam sensor gives the same result, then there is not that much left what can be wrong. Did you use Mopar sensor?
Did you measure all 3 CPS wiring to ground as well, to be sure that its not a wire insulation problem?
Further then that, i can only come up with the PCM, or a mechanical problem inside the engine. I have never tried it, but if its possible to see the cam sensor target wheel through the cam sensor hole (with a small mirror and flashlight), you could see if the target wheel is turning when you turn the crankshaft by hand. You can put a large socket on the vibration damper bolt and turn it clockwise. Then at least you are sure that the target wheel is not loose or any other mechanical problem prevents it from turning.
Did you measure all 3 CPS wiring to ground as well, to be sure that its not a wire insulation problem?
Further then that, i can only come up with the PCM, or a mechanical problem inside the engine. I have never tried it, but if its possible to see the cam sensor target wheel through the cam sensor hole (with a small mirror and flashlight), you could see if the target wheel is turning when you turn the crankshaft by hand. You can put a large socket on the vibration damper bolt and turn it clockwise. Then at least you are sure that the target wheel is not loose or any other mechanical problem prevents it from turning.
Yes, checked all three wires for short to ground or each other. Harness seems clean. Wondered about internal mechanical failure as well. Not having a lift, it is going to be tough to visualize the trigger through the sensor hole. Guess I will try but looks like the Jeep is dead at least until next weekend. Thanks for all your help. Please keep an eye on this thread for a while as I am not giving up yet.
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If it will be impossible to see the cam sensor tone ring, then the only way to see it clear is by removing the valve cover.
The ground lug G200 where Milous was talking about, also supplies the ground to the SKIM, the imobilizer module, besides for many other components. How is the SKIS key symbol on the instrument panel, is it coming on when switching ignition in run and will go out soon thereafter?
I don't say that this ground can't be the problem, but also don't see any interconnection with it to the stored CPS fault in the PCM.
The ground lug G200 where Milous was talking about, also supplies the ground to the SKIM, the imobilizer module, besides for many other components. How is the SKIS key symbol on the instrument panel, is it coming on when switching ignition in run and will go out soon thereafter?
I don't say that this ground can't be the problem, but also don't see any interconnection with it to the stored CPS fault in the PCM.
I think we both may be missing the obvious here. If the Jeep jumped time or broke the timing chain (unlikely as it failed with a miss then no restart, not a lockdown), would it likely not show the same cam sensor position fault?
I should add that, yes, the security symbol indicates as it should and goes out. I checked my door frame bus wireing (earlier post) and it came back clean. At this point really thinking either computer or internal.
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Not sure what you try to say here. You still have the same cam sensor fault code. The fault code you are having is regarding the cam position sensor circuit, which seems to be electrical, but the PCM is looking for pulses from the cam sensor, because it sees the pulses from the crank position sensor. If for whatever reason the target wheel doesn´t pass the cam sensor, the PCM doesn´t know this, but probably will suspect something wrong electrically.
I would at least check the mechanical part out, before buying an other PCM
Allright. Gave up on this last Fall and bought another used Jeep (98 6cyl). Back into it now assuming timing chain issue. NOT an electrical issue. Engine is apart to the cams exposed. Chain was thrown completely off the right side (cam position sensor side) cam drive gear. Still in place on the left side but likely has "jumped" teeth. How do I set TDC (I understand that I ultimately need exhaust but finding compression first is likely the way to go)??? Compression tester is showing me nothing turning by hand (only option unless I spin the engine with a drill/impact driver). I am betting everything is out of sequence. Where do I start? I have not pulled the timing chain cover yet because I wanted to see the TDC mark on the balancer.
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