Hey guys,
My BIL has a 95 Jeep that belongs to his friend in his garage right now trying to figure out why it die/won't start. It is a 95 4-cylinder automatic. The fuel pump relay isn't clicking on with the key on,but if we jump terminals 30, and 87 the pump runs. Also the auto shutdown relay doesn't operate either yet on both of these relays we have power all the time at terminal 30,and with key on we get 12 power to the 86 terminal I think (maybe 85 I forget), but regardless we are getting power that should click the relays,but the don't operate. If we remove the relays ,and put power between 85-86 we get the relay to operate so they are good. I didn't see any blown fuses at all.
The other odd thing is we don't get any lights on the dash when going power on aside from the seatbelt warning light from time to time,and the brake light when you go to the start position. The engine cranks, but doesn't start. The fuel pump works. No check engine illuminating when turning key on and off three times like any other Chrysler I have ever worked on of that vintage. Actually I would think we should get some sort of lights on the dash when key on, but nothing.
Computer? Ignition switch? Ground problem? Other?
Any help would be appreciated. I know I didn't provide much info, but maybe you gurus can point us in a direction at least instead of us chasing our tails.
Chris
Dunno about the no-start (except I'd start by looking for a blown fusible link), but the cluster connectors on those were known for corrosion. Jeep even had a bulletin and you can buy a New and Improved! connector throught the dealer.
EvanB
SuperDork
12/22/11 10:05 p.m.
Wrangler? Cherokee?
Does it start in neutral? That is the extent of my Jeep diagnosis skills.
I'm going to guess the ECM isn't playing. It controls the fuel pump and all the dash lights, etc. Is it getting power to the computer? Does it have spark when cranking?
ECMs are a common failure. The relay issues you describe are explained by that. The ECM provides grounds for those relays. The supply and ground for the relays will be fine. You can jumper across the terminals and everything will be great, but if the ECM doesn't ground the relay, it won't work on its own.
I agree with frankenstangsghost... spark when cranking?
Other common failures are crank position sensor (which usually causes longer-than-normal starting) and cam position sensors (which shouldn't prevent starting on an OBD1 Jeep)
Yes we are getting power to the ECM. Not sure on spark I didn't check it while I was there last night. How do we test the crank, and cam position sensors? Wrangler by the way I should have said that. Is the ECM an expensive part? Is there a way to test it?
No gauges/check engine points to cps sensor. Pretty common.
Unplug the crank position sensor, your gauges should come back to life with key on. That is a decent test to zero in on the cps, still won't start however. Sometimes you can wiggle the wires and it will start,,but I've never been that lucky.
There is a procedure for using a multimeter with the cps but I don't have q fsm now.
No crank signal should throw a check engine light, might not notice since its not running. For a 1995 you should be able to cycle the key three times and have the check engine light start blinking to get the code. Hopefully your dash lights feel like working. My 94 Cherokee wouldn’t start when I came out from work one night. Checked the code and it said no crank signal. Replaced sensor and I was on my way.
Can't check the check engine light as it isn't lighting up. None of the lights on the dash light up aside from the seatbelt warning light. Where is the cps located? We don't have a fsm either,but my BIL did fond out a few things online so far. Thanks for the help so far.
Chris
CPS should be on the back of the motor against the firewall high up on the bellhousing. Or the most inaccessible position you can put something so very important that fails regularly.
Is that the crank sensor or cam sensor?
Crank.
If it still has a dizzy, it is under the rotor for the cam position sensor.
