tugalo

Haven't looked at the alternator yet, but anything is worth a shot at this point. I am about convinced that it is an intermittent open in the ignition circuit wiring but nothing we've tried has helped, even cussing at it does not help !! What's really frustrating is the odd time when you start it up and it runs perfectly

Well, after ANOTHER crank position sensor change, the truck does the same thing. If you hook a timing light to a plug wire, and rev it up, you can see the ignition dropping out. Just to recap, we have changed 3 distributors, 4 MAT sensors, 4 crank position sensors, 2 TBS's, 4 Iac's, 2 air temp sensors, and tried 2 different cam sensors. Every so often, the truck will start and run perfectly. If you re-start it immediately, it still runs fine, but if you wait 5 minutes and start it, it runs like crap. The wiring and the pins on the computer all look good. I think we are going to go to our friendly junkie and get another computer, but throwing parts and money at it is not working so far. I remember a topic on the forum detailing a Renix repair for splices in the big harness that runs along the firewall. i wonder if the 95"s had the same set-up. My thinking is that somewhere we have an intermittent loss of signal or ground. I looked up the 95 wiring diagram on my computer, and they all show an 8V supply to the sensors and we have 7.75V on that line.

Understood Don, My understanding was that all 4.0's used a 5V supply, that's why the reference to the 8V confused me. We have checked and metered the wiring and pins.. Also disconnected the plug at the computer looking for loose/corroded pins. Hooking a timing light up to a plug wire, you can see the signal dropping out, so in my mind it is definitly ignition and not a fuel issue. I'm leaning toward 3 hosed up aftermarket CPS's. will try a new one from NAPA tomorrow.

The truck was built in Aug of 94 and all the wiring diagrams say that the crank position supply should be 8 volts. We have a 5V supply and a .02VAC output signal on a digital meter. Anybody seen an 8V supply? We did find a high resistance ground at the dip stick stud and fixed that but it still only runs good on occassion. Mostly it lopes, shudders, and backfires all the way from idle to full throttle.

The computer was changed out with one from the JY and made no difference. I'm beginning to wander if there are not some broken solder joints in the computer connector pins as shown on some utube videos. When the truck is running rough, there is a loud sucking noise from the throttle body, starting to wander about the IAC, but if the computer solder joints are bad, it may not be getting energized.

I forgot to mention that it was not throwing any codes. He has checked the timing chain and it is okay. He has had the distributor in and out several times to make sure its right. He even deliberately set it one tooth off to either side to see if that made a difference. What's curious, is that once in a while, the truck starts and runs normally, idles fine, and will go to redline without a skip. The guy is a pretty good mechanic, i let him work on my MJ when i get lazy. We were talking it over last night and he told me that he found a water leak at the heater valve which is almost over the sensor ground point so i pointed him in that direction. I also suggested that he enlarge the mounting holes on the cps and remount it. We will dig at it some more this afternoon,

Friend of mine is working on a 95 Cherokee sport, 4.0L, automatic. When he got the Jeep, it would not run. He replaced the crank sensor and now it runs, but lopes badly at idle and backfires thru the throttle body and exhaust when revved up. Very sluggish pickup. He has replaced the crank sensor with 2 new ones from O'reilly (BWD brand), replaced the MAP sensor, the temp sensor, the coil, the computer, the entire distributor with cam sensor, and the plugs and wires with no change in symptoms. He has seen the timing change 30 degrees when revving the engine. Vacuum is good and the fuel pressure is 39 lbs. Once in every 30 or so starts it will crank and run perfectly. I advised him to try a different brand of crank sensor, but beyond that, i am out of ideas. Anyone care to offer an opinion? Any and all help appreciated.

If the original Renix senders will not physically fit into your new engine, you might run into a problem with the OEM sending units on the new engine having a different ohmic value than the old Renix senders. That may throw your gauges off a bit, You will almost certainly have to change out the connectors to the senders, but removing and replacing pins in connectors is no big deal.

First test is to check the accuracy of your meter.

Splice it in yourself. There are several good articles in this forum and one of them tells you which wire colors to match an after market harness to the original wiring. i recommend either soldering or using Raytheon environmental splices instead of the normal butt splices. Easy job.

found these guys on the web and they have just about any connector and/or connector repair tools you might need to fix our weather pak connectors. they also have MAT sensors, etc. etc. customconnectorkits.com

Rotella T6 synthetic 10w-40 diesel oil

my radio finally crapped out. Looking for a reasonable OEM AM/FM/cassette radio.

Do you have a trailer towing connector? It's not uncommon for someone to hack up the wiring when installing the connector which could cause some of the problems you described. This is usually indicated by the loss of dash/instrument lights. The circuit is designed that way to let you know that you have no rear lighting. Have you tried replacing the flasher for the turn signals?

had a dodge dakota once whose left turn signal refused to work. Removed bulb, checked voltage, 12V. Hmmmm, checked continuity of the wire and it was zero ohms............hmmmm. closer inspection revealed an over crimp on the power pin of the connector, had voltage and continuity, but could not handle enough amps to function.

the suggestion of unsoldering existing components is a good one. Just make sure you put a heat sink on the leads between the component and the heat source. From your photos, it appears that you have plenty of room to do so.

I'm with you Don, A school was in 62 and memory fails.

I know that the 1156 back-ups are supposed to be good, has anyone tried LED turn/brake lights?

it sure sounds like a headlight switch issue. Are your new switches aftermarket? if so, i would go to the junkyard and get a genuine Cherokee switch to try.....

Just for grins, pull out the headlight switch all the way and insert a new PARK fuse. Then try your turn signals, brake lights, and hazard flashers.

would not be a bad idea to cut and cap the back up light harness. make sure the wires are not melted together...............eliminating one more possibility.

Good call Eagle, nothing that is on with parking lights is turned off with headlights. it would pay to remove the DOME AND HAZARD FLASHER fuses and see if the PARK fuse still blows. the only other possibilities i see on the schematic are the clock and the audio alarm. i'm guessing that the audio alarm is the chime. if the reverse light switch is disconnected, that shouldn't be the problem unless two of the wires are melted together/shorted in the harness.

Pull the INST LPS fuse and see if the PARK fuse still blows. If it does, the problem is probably in the wiring from the headlight switch to the front lighting, since you have already tried disconnecting the rear lighting. If it doesn't blow, your problem is in the instrument panel or the wiring to it. Find and disconnect the front wiring and see if the PARK fuse blows. If it doesn't, your problem is in the front lighting or the wiring feeding it. If it does blow, disconnect the front lighting the way you did the rears and try it again. If it still blows, remove all l the bulbs from the front lighting (turn sigs, marker lights), and the the PARK fuse. Get a multimeter and set it on the lowest ohm range it allows. Put one lead on Pin R of the headlight switch HARNESS and the other lead to ground. if you read a low value, you have a short in one of the blue wires feeding the front. the other possibilties are the clock, the audio alarm, or the headlight switch itself. Junk yard to get another switch from a Cherokee if required. My money is on the headlight switch.

I would suggest tackling the light issue first. According to the 88 wiring manual, there is no brown wire going into the headlight switch, there is a tan wire on the output side of the switch that feeds power to the headlights, the beam select switch, and the headlight delay module if you have one. The PARK fuse feeds power to the headlight switch and the switch then sends power to the rear taillights, the license light, and the INST LPS fuse. Pull the INST LPS fuse and see if the PARK fuse still blows. If not, then the short is in the instrument panel on the output side of the headlight switch. If it still blows, you could have a bad headlight switch. Make sure that you connected the ground lug to the headlight switch. Fix the instrument panel ground and the rear lighting ground. Until you know that your grounds are good, you are shooting in the dark.

I just ordered a pair of 1156's for my backups, glad to hear that they are a good deal. Has anyone tried the 1157 LEDs in the brake and turn slots? I understand that the lower impedance can cause rapid blinking or other problems.....