help dead jeep

so im driving along and put my turn signal on and my Xj dies.. it stops runnin and acts like i just disconnected my battery.. so the fallowing day i take my steering column apart and inspect everything, change out my ignition switch for a new one and putt it all back together... the jeep ran fine untill i turned on my heater and then it died again.... im pretty sure i have some kind of short somewhere.. does anyone have any suggestions? or have you had this problem? please help me??? My XJ is a 1990 larado w/4.o engine and auto trans:repair::repair::repair::repair:

Check/ clean all the battery conections, the grounds next to the battery and from the block to the firewall. Maybe your battery is going bad or alternator not putting out. Start with the easy stuff.

i already checked all my grounds that i know of and cleaned a ton of connections my battery and alt are good.. I'm thinking it must be some sensor or control until maybe the computer....i did all the small stuff before reaching out for some help!!

if i let the XJ sit for 5-10 minutes after it loses power, it starts most the time. a couple of times it took over night. could it be some kind of relay ,,,,please give suggestions guys and gals... thank you

Have your battery load tested. How did you check yur connections, with your eyes, or did you remove, clean , and refresh them?

It could be a coincidence that when you turned your turn signals on or heater you lost power.
If it's not related to a shorted circuit somewheres then:

Sounds like a thermal breakdown problem.
Two things come to mind if that's the case:
1. Crankshaft Position Sensor
2. Ignition Control Module or your coil

1. The symptoms point to the Crankshaft Position Sensor (CPS or CKP) on the bell housing. Inspect the wires to the CPS, make sure the connectors are clean and firmly connected. Look for any chafed or melted insulation and for any pinched or damaged wires.


2. It could be your Ignition Control Module or your coil. You should have 12 volts to your ICM with key on. If you have 12 volts to your ICM then use an inline spark checker to check and see if you have spark from the coil to the distributer.

i did remove, clean , and refresh my electrical connections. i even replaced a few that would not clean up. im going out to try all the suggestions i got last night. hopefully one of them works will update post tonight.. again everyone that has helped

Did you get the UBER critical grounds on the dipstick tube? ECU/ICM/o2 sensor and others there. The braided strap from the rear of the head to the firewall is a nightmare; replace it with a 4 or 2 gauge cable. Strip grounds to bare metal, treat with an anti-corrosion agent, make the connections TIGHT. Check for brake/clutch MC leakage down the inside of the firewall, brake fluid will attack the fuse block.

IF you can identify the missing element when the engine won't run we can give you better ideas of what to check.

When it won't run, do you have spark? Do you have 12 volts to the ICM? Does the fuel pump prime? Those kind of things will narrow the field.

Good luck.

PS--there are a number of poorly engineered electrical circuits on the XJ. HVAC switch/blower motor, headlights, ignition switch. All of these tend to overheat and melt connectors or give poor performance and should be looked at.

You can measure the resistance of the crank sensor, should be 200 ohms + - 75 ohms, or a range of 125 to 275 ohms. If the resistance is near either of the extremes, replace it.

when it dies it seems to be lack of electrical power... the whole jeep acts like I just turned my key off, no matter how i turn the key it just acts like the key is off, I replaced the ignition switch, and that didnt help ...today i tore out the entire dash board and all fifteen toggle switches for aux lights,fans,amps,horns,converters. I did find two broken wires down by the brake pedal and the connector they went to will rewire tomorrow.. i also found the fuse block to be socking wet and a couple of wires blackened and slightly melted will also be rewiring those tomorrow too. some previous owner also put the darn heater on the turn signal fuse on the fuse block. Im pretty sure from the mess I found behind my fuse block that I no WE have found the problem. I will pdate this post after i get all the repairs done... THANK YOU EVERYONEeace:

jgotmud said:

I replaced the ignition switch, and that didnt help ...today i tore out the entire dash board and all fifteen toggle switches for aux lights,fans,amps,horns,converters. I did find two broken wires down by the brake pedal and the connector they went to will rewire tomorrow.. i also found the fuse block to be socking wet and a couple of wires blackened and slightly melted will also be rewiring those tomorrow too. some previous owner also put the darn heater on the turn signal fuse on the fuse block. Im pretty sure from the mess I found behind my fuse block that I no WE have found the problem. I will pdate this post after i get all the repairs done... THANK YOU EVERYONEeace:

Click to expand...

I don't envie you or your electrical adventure.
Sounds like you are trying to do too much stuff at one time, which in turn might make it harder to trace down your main problem (dead Jeep).
Lotsa luck to ya.

the wife doesn't like me spending money on modifying or upgrading the jeep since it is my daily driver.. but my electrical night mare-breakdown works as a good excuse to upgrade and fix alot of the back yard second rate fixes that the previous owner did up under the dash..with no dash in my way it makes it really easy to trace and track all the wires...but if I can't fix it I will just rewire the whole darn thing, wouldn't be the first time just the first on this jeep.