I recently purchased a 1985 Jag XJ6 vanden plas in excellent shape. It was a single owner vehicle and I got the honor to buy his baby girl from him. Unfortunately, there are a few issue that came along with the jag that got me stumped so I come the the best Jag forum on the web for answers. Here is my issues.

The car will not turn over, When I turn the ignition key, all I hear is a click. I figured the starter was bad and replaced it and still the same thing. Autozone tested my old one and luckily refunded me on the new starter. I hear a click from a relay switch which is normal and another click or arc sound from under there the starter sits at. even with the starter completely removed. it still makes the same sound. I assume the starter is not getting power to turn. What do I need to look for?

I have a fuel tank issue but I will leave that for another thread.

 

Check the engine-to-body earthing strap. Nothing will work if this is missing or corroded.

 

The ground strap is a good place to start. It's on the right side, underneath, about where the engine and transmission come together. If cleaning the contact points there doesn't help.....

http://www.jag-lovers.org/xjlovers/xjfaq/nocrank.htm


Cheers
DD

 

Might just be dirty terminals. Wouldn't that be nice? Nice FAQ Doug!

 

That's great advice. I have the repair manual and will check that tomorrow.

 

Thanks for the troubleshooting guide. Will let you know if that fixes the issue.

 

check to see if the engine turns over using a wrench on the bolt in the front pully.(sounds like a stuck engine)

 

I haven't got a chance to check it yet (rain). I do know that the starter doesn't even try to engage, like there is no power to it. I will let you know what I find.

 

Ok, I checked to make sure the engine is properly grounded that's ok, replaced starter, still nothing. I have the repair manual and it's not helping in this issue. The starter is not even trying to engage like there's no power going to it. I was told to check for a solenoid but the only I can find is on the starter. Is there another solenoid somewere or what else should I check. I plan on testing the wiring to the starter to see if I get any kind of voltage but I'm doubting it. Any other suggestions would be appreciated.

 

Remove the white/red wire from the starter relay. Using a jumper wire, apply 12v to it. Does the starter operate?

If the starter now operates then you could have a problem with the relay, ignition switch, neutral switch, or the wiring in between.

If the starter does not operate the you have a faulty starter, faulty ground, or lack of voltage to the starter from the 12v junction post on the firewall.

I think this is all in the above referenced checklist.

(If you don't have a piece of wire for use as a jumper, remove the solid brown wire from the relay and touch it to the white/red wire. Make a mental note of where the wires go before removing them)

Post back !

Cheers
DD

 

Thanks you for the advice. I plan on checking all those this weekend. If its the ignition switch, is there a way to test that? We already tested the starter and its OK. I am also planning on testing the voltage to the starter this weekend. Thank You

 

I think the issue has some thing to do with the neutral safety switch. I read that I can short the two wires to bypass it. I see two sets of wires going to the tranny , on with two wires and one with 4 wires. Which one is the neutral switch harness and what wires need to be shorted to test to see if this is the cause. The service book I have is no help to me.

Note: using a screwdriver and shorting two leads on the starter makes the engine turn overs.

 

When you say the starter relay, is that on the starter or is it located somewhere else. My service book basically makes it look like it's on the starter

 

Is the larger of the metal relays on the firewall...the one most inboard towards the center of the car.

To bypass the neutral safety switch for diagnosis simply remove the black/green (or just plain black ) wire from the relay and replace it with a wire going to a good ground

Cheers
DD

 

Thanks for your reply. I took a photo of the wires so hopefully you can tell me if one of these are the wires to the neutral safety switch. I assume its the 4 wire harness. I will try what you suggested in the morning. Thank you





The middle relay (2) clicks when I turn the key. Not sure what ? is.

 

"?" is the starter relay.

On the trans the 4-wire bundle goes to the neutral safety switch. In "N" or "P" it grounds the starter relay. It also operates the reverse lights.

#1 in your pic is the diode pack for the fuel pump circuit.

#2 and #3 are the "main" and "fuel pump" relays.

Cheers
DD

 

Thank you doug for your patience. Obviously I'm no mechanic by trade. I'm learning. I finally figured out the correct relay and what you've been asking me to try. I tested the neutral switch using your instruction and still didn't work. I then applied power the red/white wire and the starter works. I'm almost completely convinced it's the starter relay. Is there any easy way to isolate the ignition switch being the problem before i order a $100 us part. I plan on ordering it tomorrow and keep you posted once I receive it. Thank you!

 

Use a 12V test light to check for power at the starter relay. The power is supplied to the relay's white/yellow wire only when the key is in the start position.

The relay also needs a good ground which goes through the neutral safety switch. I am not sure of the color of this wire, but it is connected to terminal 86 of the starter relay (which is also labeled W1). The relay may have to be removed to see the labeling of the terminals on the bottom.

Disconnect the white/yellow wire and the 86 ground wire from the starter relay.
Connect the test light between these two wires, turn the key all the way to Start (in Park or Neutral), and the test light should light if the ignition switch and wires are good. If the light works at this step, it is probably the relay, but double check for power on the brown wire at the starter relay. If brown is getting good power, go ahead and replace the relay.

If the light does not illuminate, then use a different source for ground, such as the negative battery post instead of the 86 wire. Then retest by turning the key to start.

If the light then works, the problem is somewhere on the ground circuit that travels from the relay to the NSS, and then to chassis ground.

If the light still doesn't work, then no power is getting to the white/yellow wire and the most likely cause is a bad ignition switch. You can move the test light up under the dash and verify power is present at the brown wires, and see if power appears on the white/yellow wire of the ignition switch when the key is turned. Replace the ignition switch if no power comes out on the white/yellow when turned to Start.

My car came with a bad ignition switch. It would actually crank and try to run but die as soon as the key was released.

 

I want to thank everyone for your excellent help. I finally figured out the problem and it turned out it was the neutral safety switch. Bypassing it as Doug explained worked like a charm. The key was I had to read all the instructions carefully because I tested it incorrectly then thinking it was the relay switch. I may have a couple more questions about this car but I will open a new thread relative to the issue. Thank you all so much.

 

Ok I have another quick question, since it does pertain to the starting issue. I now can turn over my car but it's not cranking. I think it's a fuel issue so was wondering what I need to check so see why the engine is not firing up. I have a volt meter that I can check the ignition coil, how do I check the fuel pump to make sure it's sending fuel through the line? What else to check.