I have a 99 XJ8, with a very annoying intermittent starting problem that I hope someone can help me with. The car will start fine for several weeks and then suddenly refuse to start. I arrived home on Thursday night, and when I went to start on Friday morning - nothing.

All that will happens when you turn the key is the solenoid click.

I have had the starter and battery both checked and they are both working fine.
I have confirmed that I have the correct voltage at the starter.
I have taken off and cleaned the ground strap.
I have even gone so far as to run a wire from the solenoid connector to the top the engine and shorted it to the battery connection coming out of the false firewall.
I have swapped out the starter relay.
I have tried starting in both park and neutral.
I have cleaned all the connections around the two fuse boxes.

All the above has not helped to start the car.

This has happened a couple of times before. I went through the same troubleshooting steps with no success. Then suddenly the car starts and then continue starting for a couple of weeks.

Is there anything that I have missed - some magic incantation or test that I can run?

Any help would be appreciated

Steven.

 

There have been several reports of either battery cable not making good contact where crimped to the post connection. Also check the connection to the big fuses in the trunk and the bulkhead in the engine compartment. It's always possible the ignition switch or starter solenoid are at fault, but I would continue with wiring first, as you have already done.

 

Steven,

You've done lots of good diagnostics so far, and I agree with RJ237 that the ignition switch is a very likely culprit. A couple of other possibilities are:

1. The Body Processor Module (BPM) contains the Engine Cranking Control circuitry, and BPMs are known to develop problems.

2. The Key Transponder Module, which is part of the security system and is connected to the BPM and ECM. It allows or disallows starting depending on recognition/authorization of the transponder in the key.

Search the forum for additional information and please keep us informed.

Cheers,

Don

 

Thanks for the replies.

I have also tried shorting the two connectors on the starter which to my mind would exclude all the circuitry and provide the necessary 12v to the solenoid. All I got was a click. If I am reading it correctly, I am getting the right voltage to the starter - 12.4v the last time I checked, but perhaps not enough amps. The battery is only 4 months old, and as I mentioned, I have had it checked by the local auto parts store.

When I am totally frustrated and continually try the key, about every 30th time the starter kicks in and the car tries to start. One time this morning it did start, but then not again.

I have cleaned - contact cleaner and file - all the battery connections I can find.

How does one test for the BPM?

I am assuming since the car doesn't start when I short out the solenoid circuit, that the key transponder module is not in play. One reason for my assumption is that I have only 1 key - and I have heard horror stories about the price to get another.

Thanks again for the replies.

 

Measure the voltage at the starter WHILE you short the solenoid circuit. If it remains at 12 volts, then you've got a bad starter. If it drops off badly, then the problem is elsewhere.

 

As I was putting everything away for the evening, I thought I would try the car one more time - wouldn't you know it - it started the very first time.

I will have to see what delights it holds for me in the morning. Part of me wants it to start, the other part of me doesn't want it to start so that I can continue to troubleshoot and find the real problem.

Steven.

 

Started well all day, until I tried early evening. Back to troubleshooting next weekend, luckily I don't depend on it.

 

I think you may need to have your key reprogrammed by a dealer or indy with the right software. Had this problem year ago: would start with one key set, but not the other. With both key sets all the dash lights came on. Took both keys in the car to an independent, he reprogrammed both keys.

 

Thanks for the suggestion. If the key needs reprogramming, can it manifest itself as an intermittent problem? Also, would the solenoid click when I try to start?

Steven.

 

After thinking about it for the week, I went back to basics and started from the beginning. I pulled the starter to make sure it was working properly, even though I had it tested about 2 weeks ago.

I jumped it off the car and the gear would shoot forward but not spin. I took it to my local Autozone and they confirmed a bad starter.

I installed a new starter and the car started first time. Hopefully that is the end to the issue.

I appreciate all the help working through this frustrating problem

 

Good job. Sometimes you need to go back to basics.

 

Steven;
I had the same problem on my 1999 Vanden Plas.
I could tighten battery and it would start or jump it would start and then nothing.
I finally cleaned a and redid connection under hood passenger side in front of fire wall where CPU is hidden. there is a connection that is a like a through bolt to weather and dust proof CPU box. Since then no problem getting the car to crank after two years.

Larry