Topic: Jeep dies when I hit a bump

[Got Wood?]

I have spent some time searching but I have had no luck, so now I am forced to ask for some help. 97 tj 4 cyl. auto.(wife's Jeep, although she refuses to drive it until I get the problem resolved) A few of weeks ago I was driving and hit a large bump, Jeep dies, headlights still on, cranks but no start. I coast into a parking lot, and it still cranks but won't fire. I park it and got to the fuse box under the hood thinking something had gotten jarred loose, like maybe fuel pump or asd relay. I rearrange the relays with the a/c and horn relays and get back in, starts right up and I drive it home. Meanwhile when it has been really cold, on occasion, the starter would crank a couple of times and then the bendix would release and the starter would just spin. Last sunday I changed the starter, when I hooked the battery back up and went to test the starter it cranked fine but once again no fire, checked the gauges and noticed they were all dead, as if the key was off. Started playing with the relays again, this time I honked the horn which told me that ralay was working, swapped it with the asd relay and it started. Tuesday evening the wife heads off to class, and then calls me and says she went over some rough rail road tracks and the Jeep dies, cranks, has lights, no gauges and no fire. I explain the relay trick which seems like a quick fix, but now I am not sure, she has no luck. So I head out to rescue her and she calls me back and says it finally started and she got it off of the street but she wanted to wait on me to escort her home. I drove it home and now I am at a loss. It seems the only way to get it to die is to hit a hard bump, I guess I need to find an empty parking lot with a sizeable bump so that I can kill it to try to find the source of the problem. Any help would be greatly appreciated.

[jonzjeepyj]

OK,  The first time it happened I had it towed to a friends garage and it was diagnosed with a bad ECM.  I found one locally and it worked intermittently on the lift and was working when I got it back.  It drove fine for about 3 days.   It shut down on me twice and the final time it left me stranded .  I towed it back to my house, with the wife's Suburban.  The ECM was purchased and replaced.

I have replaced...

ECM                               New / Christiana auto parts  325.00
Fuel pump/sending unit    New / Quadratec                 200.00
Crank sensor                   New / Christiana Auto Parts   69.00
Coil,Cap,rotor,wires,plugs New / Christiana Auto Parts   82.00
Cam Sensor                    Used / Omegatheway             N/C

I used an OBD I and looked at all sensors while running.  2 Days ago they were all running within specs.   
Then I went for a ride and it happened again.  After spending a lot of money and time to find this problem
I started tapping and banging under the hood while it was running.  It cut out on me again when I tapped
around the fuse box.  I did the same thing by swapping the fuses and relays around but with no luck. 

I found it to be not the relay but where the wires push into the bottom of the blade holder in the fuse box. 

Undo your clips and flip your fuse relay box over and wiggle all the wires to see if there are any loose wires and
see if you have same problem I had.  I found the loose wire and pushed it back in the blade holder and it solved
the problem for good.

Let me know what you find,

John

 

[Got Wood?]

Thanks for the reply, I just went out and beat on my fuse box with the jeep running and had no luck, it wouldn't die. But last week while trying to figure out the source of my problem I took the back off of the fuse box. I did notice a little bit of green in the back of the box on what appears to be a buss bar. I pushed on and wiggled all of the wires, didn't find anything loose, but I could have pushed it in tight before I tugged on it if there was a loose wire. I guess I will find a big bump in a non-busy road and see if that fixed it. Anymore input is appreciated.

[dexetr30]

cps?   
I had a similar problem on a 2000 Sport I owned in the past. I'd hit a bump on the trail and it would suddenly shut off. Did you check to see if it's throwing any codes? What about the fuses? I'd look for simple things like fuses or sensors before checking the cps. Good luck.

[aw12345]

Since a bunch of stuff goes dead you have a power feed wire problem, The dash and such feeds of a circuit that goes to the ignition most likjely you have a poor connection in a wire that comes of the starter or of the accesory fuse box under the hood look at all the thick wires and any type of connection that they might have look at the bulkhead connector also. While its running wiggle all of these connections. Or put it up on some good size wood block or what ever and drive it of to get it to die so you can figure out which circuit goes dead its so much easier to find when its acting up then guessing at it afterwards. If you can get it to go dead  I would start looking at anything that feeds the instrument cluster as well as the power cicuit for the fuel pump and asd relais. A cranck sensor would not make the instrument cluster go dead. Its a power feed problem just up to you to find the particular circuit, a wiring diagram would help to find what several cicuits have in comon can be a great help in narrowing down your search area

[Got Wood?]

I caught a break today, I got in the wife's jeep and tried to start it to move and had no gauges, no start. I then started wiggling all connections under the hood and had no luck. I then decided to try beating on the dash since the gauges weren't working either and they came on. I started the jeep and pulled it into the garage. I decided that the gauges had to be a symptom, not a cause so I wiggled the tilt steering column up and down and that made it cut out. After disassembling most of the column and removing the wheel I finally found there is a bank of plugs behind the driver's side lower dash. Started wiggling plugs and finally found one that made the gauges cut out when wiggled. I then found that plug was not snapped in all of the way. I pulled the plug out, sprayed it down with some electrical cleaner and plugged in back in ensuring both sides snapped in. I am feeling confident this will solve my problem. In hindsight it seems so simple but with the problem being intermitten and difficult to duplicate it just took a little time.