dkross

My daughter's jeep has been having issues for he past month or so. It started by dieing after she would start it. Now it is dead in the school parking lot. The jeep is a 96 XJ 4.0l, AW4.

So far I have cleaned all the grounds and added new ones to the firewall and engine, and from the battery to the engine and front radiator bracket. I have replaced the CPS, coil, battery, and ASD relay. I have continuity from the power distribution block to the plug going into the coil. I also cleaned a connection underneath the PCM or ECM. I have pulled the plugs on the ECM and put dielectric grease on them as well. I have cleaned the connections at the alternator and starter. New battery terminals when the battery was replaced. I also repaired some bad sections of wire on two of the four wires from the loom coming from the harness at the fuel rail to the upstream o2 sensor.

Readings on the fuel rail have been strong at 51 psi while running. The fuel pressure will maintain pressure and only drop 10 psi over a 20 minute period. You can hear he fuel pump run when the key is turned on.

The jeep gets 9.3 to 9.6 volts during cranking to the plug feeding the coil with the new battery. A tune up was done early this summer with cap, rotor, plugs, and wires. I also replaced the TPS this summer as well. I put my scan tool on the jeep last night and it threw code P0351 which refers to "Ignition Coil 'A' Primary/Secondary Circuit Malfunction'. Given the coil is new and is only receiving 9.6 volts (should be 12V from what I have learned) while cranking would the next step be to replace the ECM?

Thanks for the help folks.

DFlintstone

If it's not getting spark I'd check the cps output, sooo easy. (1/2 volt ac from it cranking). New ones can be bad. If is says the coil is bad I'd consider testing the new one or trying another, maybe the one you changed out. A coil should fire with 9 Volts. And wow, sorry man, what a *****!

Bustedback

What is the voltage at the battery when cranking?

cruiser54

That's for Renix. Not sure on the later models. Man, the OP has done all the right things. I don't know how the PCMs like low voltage on cranking though.

dkross

I did not put a multimeter on the battery while cranking; however, prior to checking the volts to the coil I checked the volts on the battery as it was sitting and it has 12.2. I usually do this to make sure I have my multimeter set to the correct setting. Like I mentioned in my original post it is a brand new battery, just a week old.

Thanks for the replies guys.

DFlintstone

"That's for Renix. Not sure on the later models." < Thank you Cruiser.

You do have no spark?

It's still the same basic setup. Magnet on flywheel/torque plate flies past a small coil making a small voltage spike. But at the moment we don't know WHAT voltage. The small clips on my leads makes it supper easy for me to see IF it's putting out a signal.

I noticed on a parts list for a 96 there is such as a thing as an "ECM Wiring Relay" Honestly I'm clueless, just wanted to share that. (on the outside it's just a little cube like the rest).

dkross

DFlintstone,
Originally, I did not have spark which lead me to believe the coil was bad and so on. I did not check for a no spark condition the other night though.

I just got off the phone a few moments ago with the local napa store. I was gettign ready to pull the trigger on a PCM. Fortunately, I know the guy behind the counter and he has a pretty solid mechanical background. He asked about the pick up coil. That is the one thing I have not replaced. I had forgotten all about it being a possible problem. I went ahead and had him order a pick up coil for it. It will be in tomorrow morning and that may tell me what I need to know.

I will look into the ECM wiring relay though. It may be the next step.

Thanks

dkross

Replaced the pickup coil on Saturday and the jeep is running pretty well. That may have been the culprit all along. I am going to drive it for a few more days before I had it back over to my daughter.

Thanks for the help guys/