girlfriend was driving our 95 jeep grand cherokee 4.0 and it just suddenly died as if the key was turned off. After dying it would crank but not start . had the jeep towed 120 miles home.

Replaced: coil, wires, plugs, crank sensor, ASD relay, timing chain (was time anyhow).

DTC codes: 43 Spark/ignition control circuit problem
42 Automatic shutdown (ASD) relay circuit problem
47 Battery voltage sensing circuit problem (volts too low)
21 Oxygen sensor (this has been disconnected for over a year)

when I try to clear codes with innova 3120 CanOBD 2&1 diagnostic tool it just thinks forever without clearing codes, yes Im sure im doing it right. Disconnecting battery did not clear codes either which really confuses me.

I am at a total loss, no fuel or spark, which I assume is a result of the auto shutdown. Tried jumping terminals 87 and 30 of ASD relay and still no start. Tried jumping terminals 87 and 30 of fuel pump relay and cant hear the fuel pump run. Wondering if there is a shut off switch somewhere that needs to be reset (like after an accident) or if this vehicle even has one. Its somewhat unclear based on what I've read so far. Current thoughts are either the fuel pump, fuel filter, or the brain. I have put a lot of money into this already and dont want to just keep replacing stuff untill it works (which is what I normally do) any help would be greatly appreciated.

 

Check for power and a pulsing ground at primary plug on the coil. You may need to replace the pickup coil/ cam sensor.

 

With the key in the on position I used a voltmeter and tested for power at each wire going into the plug on the coil. One side read 13v and the other 6v but it was not pulsing. Did I test this correctly? I really appreciate your help I've been struggling with this off and on for about a month now. I am not real experienced so I have to read a lot at every juncture. then I am not confident in weather the part is bad or I tested it wrong so I just replace it but that is getting expensive. On the bright side I have a lot of back up used parts now.

 

The ground should pulse while cranking the engine over, use a 12volt testlight with the probe on the primary ground wire and the clip on the poss battery terminal. The light should flash when cranking. If it stays lit or does not flash it could mean the pickup coil/ cam sensor is bad.

 

well im doing the unthinkable...... mechanic. I have never done this but my father in law offered to pay for it as our Christmas present. I tried to test the pick up coil and had no power to the positive end and therefore could not even test the pulsing ground. the thing is on the last test i did have power to the live wire so i don't know. I'm at a loss at this point and since someone else offered to pay for it Im no longer perusing it anymore. I will post the final results from the mechanic when they are available. thank you so much for your time. i really wanted to figure this out myself but priorities got in the way.

 

Hey man, don't be too proud to let him pay for it. Just find out what it was and store that info in the old bio-file.

 

i would say check the cam unit located under the cap and rotor u jeep guys really over look this part at times on the straight 6's

 

Well I took it to the mechanic and it was a 4 dollar fuse. At some point I blew a fuse while changing out or testing relay's and apparently never checked it again. I changed the coil, crank position sensor, distributor cap, plugs and wires, and relay's. The relay is the last thing I changed which is also when I lost power to the coil so I'm assuming one of the parts I replaced went out as well as a relay and when i replaced the part it still didn't start due to the bad relay and when i replaced or probably when I tested the relay I blew the fuse. So in the end I created a new problem while fixing the original problem and didn't think to go back and check the basics again. I felt pretty intelligent when the mechanic told me he replaced a fuse and I owe him $95. Anyhow thanks for all the help. Never changed the pickup coil/cam position sensor.