Im at a loss here. I have a 93 Jeep Grand Cherokee 5.2 L
While driving my Jeep the other day i get a Check engine light that popped on, immediately i noticed a voltage drop on my gauge, and the car began to sputter, bucking and wanting to die in the middle of an intersection. I was about 1 mile from home, and wound up limping it to my driveway (thankfully).
I got the OBD code for a bad TPS sensor. No problem easy fix. I go down to autozone grabbed the new TPS (duralast), and install it without issue. I turn the key in the ignition, the car fired over and died about 1.5 seconds later. I attempted to start it again but the motor just cranks and cranks but wont fire.
I figured its possible i have a bad battery/connections. Get new connections for the terminals and have the battery tested. Those are all good. I attempted to start the car again, same thing. Crank but doesnt fire.
Out of curiosity i take off the new TPS sensor and put back the old one. Last time i tried to start it with the old sensor it started, but just ran like crap. Same thing, car cranks wont turn over.
Checked spark plugs and wires - good
Had replaced cap/rotor etc 1.5 years ago
Checked air filter - good
Checked alternator - good
Hooked the car up and tried to jump it - check
Disconnected battery overnight thinking the computer may need to reset.
Fuel filter - its good
Checked to see if it was getting fuel to the fuel lines - check
At this point i am out of ideas. Has anyone come across something similar, or have an idea of what to do next. I did a search on multiple forums and couldnt find a problem that was exactly like mine. I did see that some people say that the after market TPS sensors are crap. Any ideas or clues would be much appreciated.
(i hope i posted this in the right section, my apologies if not)
Flash....Can you give us a current status on what your Jeep is doing at the moment. I.E, It will start and run with poor idle, Still trowing a code for TPS, Alt voltage is ????? when checked with a multimeter. ECT.
Currently it starts, idle rough (sometimes dies), idle surges. Still throws a code for the TPS, will sometimes throw a code for the 02 sensor (21).
22 Engine coolant temperature sensor above or below acceptable voltage.
23 Intake air temperature sensor input above or below acceptable voltage..
24 Throttle position sensor input above or below acceptable voltage. TPS signal does not correlate to MAP sensor.
46 Battery voltage too high during charging or charging system voltage too low
Of course i will get the code 12 for battery disconnected.
The only static code though is the 24 and 46
Looks like i might be able to get a reading on the alternator tonight (weather permitting)
With all of those codes coming up that have something to do with voltage, getting that alternator reading im sure will go a long way to figuring it out. Every time i get some spare time to work on it, i get rained on. Days i have to work all day its been sunny, go figure =)
If it were mine I would say a bad alternator and a vacuum leak at or around the throttle body. I would have the battery load tested and make 100% sure your battery connections are clean and tight.
Got home, rain an thunder going on. But, I got it to start And just got it to hold an idle by holding up the PCM wires. Going to try that again here when it stops raining, and get that alternator reading
Yep, looking like its the PCM wires that is the cause of my problems. I had checked them before, well actually had my brother check them while i was in the cab. Apparently he wasnt holding the right wires. Soooooo Saturday project (looks like it will be sunny) is to do the zip ties!
That you can clean, regrease and zip tie the wires back to PCM. Is this only for the later models, or is it something i can apply to the 93 Zj? If it does not apply would that mean i would need to do the capacitor fix in this thread? http://www.jeepforum.com/forum/f13/fixing-lazy-pcm-new-caps-writeup-501951/
I recommend the zip tie fix to be used as a troubleshooting step on the later model ZJs. The earlier OBD1 ECUs have a different type connector and arent prone to solder joint failures, though it's not impossible. My take-away from reading here on the forum, these connectors are more prone to having pins pushed back, which can mimic the loose solder joint problem on the OBD2 vehicles.
In your case, if there is a failure at the ECU, it will most likely be a pushed back or loose socket in the connector. Cap failures on the OBD1 ECUs generally will not cause a code. It never hurts to replace the caps though.
Took apart the PCM/ECM (not sure which is correct), and it was pretty dirty inside. So used contact cleaner and cleaned it out real good and pretty like. Synched up the cords with some zip ties, and it seems to work.
Well the saga is ongoing. Ran it for 15 miles and some new symptoms. High idle and voltage drops, this time with code 44, which is ECM code. Looking like a new ECM. Time for more testing.
also, i dont have the book on the 93 but for a 95 code 44 is:
An open or shorted condition exists in the engine coolant temperature sensor circuit or a problem exists in the PCM's battery temperature voltage circuit.
the battery temp problem would correlate to your voltage surges.
Interesting, I must have read the wrong obd code. The jeep is at my friends right now, couldn't drive it home. So, I'll double check the code. The rpms at idle is constant at 2k. Drops down when in drive, no real surges. But I do think that as the volt dropped the idle did as well now that I think about it
have you taken the ECU connector off and checked its sockets? the wiggling is a dead giveaway.
also, with the various codes you have had throughout your ordeal, i would suspect the common ground for the sensors you have mentioned.
I'm not a v8 person, nor an OBD1 person, but i recollect that the engine sensors are grounded somewhere on the block, unlike the OBD2 models where the PCM furnishes a ground.
Yes I took off the connector yesterday, used contact cleaner in there, let it dry and then reassembled. Is the battery temp sensor something I should get from the dealer, or is that one ok to pickup at napa or autozone?
Theoretically, if there was dirt still lodged in the female end, could that be the issue? I didn't pay as much attention to the female end as the male end. If theoretically that could be the issue, making it not seat correctly, I'll go back in and try to clean that more. Heck of a lot cheaper than a new ECM.
yes, a small amount of dirt will cause problems. if you havent flushed the sockets (on the harness connector) out with contact cleaner, dont worry about a battery temp sensor yet. use copious amounts of cleaner in each socket. use the little red tube to direct the cleaner down each hole. be sure to turn it away from your face. dont ask me why i'm cautioning you about this...
then if you have compressed air, blow the sockets out while the cleaner is still in there.
Lol, i will not ask you why. But if it has anything to do with a similar experience i have had with contact cleaner, yeah i feel your pain. That will be my project hopefully tomorrow. Once again thank you Zeejay (and everyone else that has posted in the thread) for all that you do.
something else you should condider while your connector is off... check in #1 of the dirty dozen and click on the link for restoring the tension of the contacts. it takes a modified dental pick, but may be worth your time if the sockets are the same type as an OBD2 unit.
Was looking at that and wondering if those caps might be the issue. Certainly a cheaper fix than a new ECM. Ill do the cleaning first, then attempt that before purchasing a new one. I know a person with a sodder gun, and will probably have them do it. As i have never used one before, from the sounds of it though it shouldnt be to hard.
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