IT'S BACK...Just when I thought it wa see to come out of the water...New Starter, and it Still Won't Start!

Well Ollie, what do we do now?
New starter installed in the vehicle, 700.00…I’m happy! The next day it starts up again…happier.
Yesterday is was cold and wet here in Syracuse, and windy too. Not needing to go out, I left her tarped and in the dark. Today we are being shined upon with 50+ degree weather and the vibes are good. I’m ready! She was not. I turned the key and instead of hearing the growler roar, and mind you there were neighbours watching, I heard click, click,click. Ok for you I said and proceeded to take out my new NOCO 2000 amp super kit. I am going to give her a shock she won’t forget in a hurry. I did and she woke up immediately. I drove around the block, parked the car, gave her the evil eye, twice just in case, and went inside. Lucky for her, and I say this with all due respect due to her age (1989) 31 years for those who need count on their fingers and find out there are not enough…she responded in kind and heeded the call.

You really need to get a voltmeter/amp reader. They are very inexpensive.

Test it on the battery +/- posts.
When fully charged, it should read about 12.5 V. If it can’t hold a charge by itself, battery is bad.
When car is idling, it should read 13-14V. If not, then alternator is not charging.
Shutdown car, and test amp draw on battery. You’ll have to see archives to see what an acceptable draw is. If it’s too high, start pulling fuses one by one to see if it suddenly falls.

My battery kept going dead when I first bought car, doing above procedure pointed to my passive seatbelts having a short. Took me a total of 20 minutes to diagnose.

Oh, and these massive V12’s take a lot of voltage to start! So even if your battery is 11.9V, it ain’t gonna turn over. Click, click.

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You need to call your mechanic tomorrow morning and let him know about this. He removed and replaced your starter, but possibly this wasn’t necessary (or maybe it was?). There are many things that can cause your “click, click, click” that have already been mentioned including the battery, cables, starter relay, and ignition switch as the most likely. Since the “click, click, click” reappeared so quickly I suspect that the real problem wasn’t found and fixed by your mechanic.



I noticed something a bit odd, but none the less…
When I purchased the vehicle, the computer was not working. I ordered the part that sits on the right bulkhead enclosed in a tiny box akin to the battery. It has 4 posts. The computer worked immediately. Today for the heck of it I tried to clear the computer and…the “inst” display would not clear from the numbers 199. I unplugged it and plugged it back in…1999 appeared. I have a spare computer and replaced the original, everything resets at 0. Could this be a short with the 199 in the display or a dysfunctional computer?

All my classic cars (and boat) have isolation switches on the battery. I have a habit of isolating the battery even if I’m only leaving the car overnight regardless of starting reliability. Handy for track work also.

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Hello and thank you for writing. Would you please explain to me what a battery isolation switch is.

Thank you in advance,


I have one too, but I only use it if the car will be sitting for more than four weeks. (Or an easy way to cut power if I’m working on electrical parts)

Google battery knife switch.

Richard. The isolation switch is a cheap screw down mechanism that connects to the negative terminal of the battery and has a male terminal for the cable connection. See pic. There are many other types but this is the easiest to fit.

I am reading about one right now! Battery disconnect or isolation switch. Greg, Thursday I handed over 700 dollars to the mechanic, who by the way is a nice guy and I am sure he will help me. Friday AM turned over right away.
Saturday, cold windy and wet, it sat under the tarp. Sunday at noon or 11 daylight savings time…nothing. Jump pack…first kick…drove around the block…10 minutes of driving, started all day. Odd…mechanic tested battery, and alternator…claims tested perfectly. I have had issues with the electrical system since last August when I purchased the vehicle. If I stopped for gas and left the lights on, within 5 minutes I needed a jump. I recently had a new alternator belt installed as the other was shredded. I also had the battery tested and charged overnight by Battery World, a local seller of batteries. Cool. This is ugly.

Hi…Thank you, I just viewed a video of the same unit. The only issue is the computer would disconnect and I would need to open the trunk every morning. I am first going to try and find the draw even though I don’t have a good meter. I have watched videos of how to do this.

Make sure you check the crank damper. A sheared crank damper can turn the alt fast enough to make it look like it’s working but not fast enough to fully charge the battery.

I have a cheap meter and the battery if correct read 4.85 volts by sitting overnight. Can’t be good.

yes, that’s a major amp draw somewhere. What year is your XJS? Do you also have the passive seatbelts like I did?

A simple light left on overnight will barely drop it down to the low 12s. Headlights wouldn’t even bring it down to 4.85 volts.

And the battery isolation switch won’t fix the problem, it will only disguise it.

Correct, 4.85V is not good. I spent a good time trying to trace down a battery drain problem. I found one suspect relay in the boot, but ultimately is was the battery at fault. I suspect you need a new one, or at least something known to be good to test with.

where did you buy the battery?! If you can take it out and bring it in, they can test it for you, for free.
Sometimes these problems are two-fold. “COULD” be your starter AND a bad battery. You can start with the easy stuff first.

An amp draw test across the battery when the car is shut off would show for sure if it’s a short draining the battery or not.

Which relay was that? I changed the relay that runs the computer.

It was the radio aerial retraction relay - very specific to my XJR-S - this is not the problem you are looking for [ waves hand like Sir Alec Guinness ] . As Greg points out, you have something drawing a lot more juice than the couple of hundred milliamps that a funky relay or bad interior light would cause.

If you have a meter, check the voltage at the battery, and at the alternator, when the car is running.

The starter is new and the battery tested ok. I am dropping it off tomorrow to let him find the draw.

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I’m surprised he hasn’t already done that, in determining it was the starter. Maybe he made a mistake replacing it, hopefully for your wallet.

Not reading the whole thread, but is it possible a light was left on? some sort of parasitic draw. I’m assuming the battery is new(ish). more times than I care to admit, I’ve flipped the map light on and didn’t notice even after the battery was recharged. Not until the car was in the dark, and turned around and noticed the inside illuminated.

I always look at the simple before digging in to the not so simple. The next step would be looking for a parasitic draw.