I recently bought a 1993 XJ6 Vanden Plas 4.0L. The lady I bought it from told me it had sat for about two years after she stopped driving it. She said her mechanic/son/whatever said it needed a new starter. Being an experienced mechanic and all-around car guy, I knew this was a load of horses**t but it had an immaculate interior and I was only paying $375 USD for it; I didn't care.

So I put a new starter in it, and it did the same thing as before. It tries to crank over, but the crank only turns about an 1/8th of a turn, then I hear all the relays click off, and then it cycles again. I figured out that some relay in the engine compartment is causing the fuel pump relay to not click on, so I put my cheater relay in and click it over by hand. Holding it on, I hear the fuel pump relay click in the back and the pump it running. I have a buddy of mine try to start it and it does the same thing.

At first I thought it may have been seized after sitting for so long, but I turned the crank, and it turns fairly well and the engine definitely has compression.

Is there any electrical issue that could be causing some sort of fail-safe to not let the motor turn over? I hear/and can kinda feel the bendix engage, but like I said, the crank only turns just slightly.

Any ideas? Thanks, guys!

 

update. I jumped the starter directly and found it cranks just fine. I'm certain it's a relay issue. Could it be a faulty neutral safety switch? The inertia switch isn't tripped. One of the six color-coded relays in the engine compartment is getting hot though. Clearly a sign of resistance, but I don't know what else to look for. The one that's gettin hot is colored purple (the harness), and if I manually trip the black one, I can hear the fuel pump relay and fuel pump click on in the trunk.

Something is causing the car to not want to start up after I turn the ignition. Any help? Thanks again.

 

another update: found no power to the coil when the ign is in the "on" position. I read that if this is occurring, check the "gearbox park interlock switch", is this the neutral safety switch???

 

Rumble,

I'd check the fuses just to make sure they're fine, then I'd check the relays. I have an older model (88) so the majority of mine are beneath the passenger kick board (no airbag). Yours I believe are in the engine compartment, rear firewall. They're various colors for different components. Sorry I can't give as much detail since mine is older. But that's a good place to start. The relays tend to become flaky due to their age.

Just my suggestion. Best of luck.

 

Rumble: Others more experienced will chime in; and my gut feeling is that you will certainly get this sorted. Be encouraged! I do know that the xj40s are particularly sensitive to low battery charge. Pretty much anything less than a full charge on a good battery might not be enough to get it to crank. Beyond that, you'll need to confirm you have got good pressure at the fuel rail and, of course, good spark. There's a fuel pressure regulator involved, which I think keeps things at 40 psi.
Others?
Cheers!
Scott

 

Spark is almost certainly the issue. Fuses were the first thing checked lol.

 

Can anyone tell me how to bypass the neutral safety switch?

 

I had a 95 xj6 4.0 and I am a little experience with them. My no start problem was the fuel pump but this is not about me. As you know it will not run without spark and fuel my question is have you put a fuel pressure gauge on to see what kind of pressure you have? You could have a fuel filter that is clogged or a bad pump. As for the spark you can check it by pulling one of your plug leads or coil pack and 1 attach a plug to it lay it on the case and see if it sparks or 2 get a spark checker and see what you got. Now I only know of one situation that the shifter selector switch allowed the car to crank but would not let it start so if you move it from “P” to “N” and give it a try. You should get a new relay and I think your car has 2 different types so get one of each and pull the old and replace with the new and give it a try. If that does not work go to the next one. I do not have a oneline for that car but I will look for one. I would like for you to look for a high voltage fuse that should be near the battery and see that they are intact. I guess you could do this by turning your key on and check your 12 volts at the terminal on each relay/fuse box, no voltage it cannot work. I hope this helps!

I found the oneline http://www.captainjaguarscathouse.co...ec%20Guide.pdf

 

Thanks Gus! I'll look for that fuse. I know it's something in the electrical system thus far, not sure about fuel yet, but I need to get the ignition to at least turn the car over before I'll even know if there's a fuel issue.

I took the neutral safety switch off to take a look at it and reinstalled it, but now there's a light on the dash showing a picture of a transmission with an "x" through it. Now, the bendix isn't even engaging.

 

Get the codes!

 

Whoah... By 'neutral safety switch' are you also talking about the Rotary switch on the side of the gearbox? Looking at the Haynes book I think you might be. If you have disturbed it's position, the whole thing is going to need to be re-indexed to the correct position. I think this may require a special tool. Or, have you disconnected something on the console end? Either way, Gus is right: what code has it tripped?

I still think, if you haven't yet ruled out the battery, certainly by now and multiple attempts to engage the starter could have worn the charge down enough to not even turn the car over.

Scott

 

I had a similar problem with my 88 XJ6 except mine wouldnt turn at all when the ignition key was turned. I don't know the name of the part, but it was a switch that told the computer what position the gear shift was in and a workaround was to put the car in neutral to start it. Good luck.

 

The car has no battery, it's hooked up to another car's full battery with a trickle charger on it while I work on the car. I put the switch back on the side of the trans, nothing has changed.

Here's what's happening. I put the key in, turn it to the on position, and a lightning bolt and a transmission with an "x" through it appear in orange color on the left side of the dash. I don't have a code reader and obviously no way to get it to a shop to get the codes pulled, sorry.

Now, I try to start it. The bendix catches, the crank turns slightly, and several relays suddenly click off. A second later it attempts to start it again and the same thing happens; this continues to cycle until I let go of the key and let it return to the on position. If I jump the starter with a 12V source directly to the solenoid, however, the engine turns over just fine.

I am getting power to the coil. I am getting fuel to the rail and injectors (provided that I hand-actuate the relay), but some fail-safe or whatever is preventing the vehicle from letting me turn it over. SO, obviously something has malfunctioned in the electrical system.

Can anyone point me in the right direction? Thanks again.

 

You need to get the transmission problem resolved first. As for the battery I would suggest that you get a battery rated for the car and install it to isolate any abnormalities from this equation. Then I would try to get the codes, write them down and clear them and then see what you have.
You need to look at your oneline Figure 1 Right & Left, to the left of the oneline from the battery you will see 3 terminals (right terminal post, jump starting terminal and the left terminal post, you need to clean them and tighten them up to ensure a proper connection. I use Dielectric on all my connection and that is my choice and you will find many that will differ. I can say it works for me! See what that does for you and with a little luck others may have more info for you. I hope this helps!

 

Rumble: I just had some work done on my rotary switch by my mechanic as didn't have the knowledge or tools to do it myself. I do know that if the position is disturbed without being restored to the proper location using a special tool from Jaguar, then you will get a gearbox fault and I can only think the car will not turn over. It won't know what gear it is in! Perhaps if you had a Jag mechanic look at it, the switch itself can be tested to eliminate the possibility of a flaky switch. I think they are generally supposed to be robust, but mine crapped out at 85K miles... This switch is sometimes also called a PRiNDLe switch after the letters of the gear options. Please see the Haynes book page 7-7.
As far as the codes go... I also do not have a code reader. It has to go the shop for the more advanced stuff. BUT, if you've got a check engine light, your dashboard computer, also called a VCM - vehicle control monitor, should display a trouble code. The car must be off and then the ignition moved to position two - without engaging the starter. You wait a second and press VCM and the code should be displayed on the dash. I think this only works if you also have a check engine light; and I cannot remember off hand if a thrown tranny fault also throws the check engine. You'll have to look. If you are able to get a code reader and/or the codes off the dash, several of us do have the service manual and can probably come up with their translation.
I'm sorry I cannot offer you too much more. I'm not much of a mechanic.
Cheers, Scott

 

Thanks a bunch, Scott!

 

I hit the VCM button and it said "FUSE 1". ??

 

I replaced a gearbox fuse, and some other fuse, and it still says fuse 1 on the onboard diag. My door locking fuse keeps tripping every time I try to lock the doors though. I'll try and replace it then just not use that button.

 

Rumble: Two more things. A "fuse 1" fault, at least on my '91 MY, suggests a blown fuse on the right/passenger side footwell fusebox. I'd systematically go through them to see what needs to be replaced. My owners manual doesn't suggest that any of these should affect the locks, but that might be different on a '93. Do you have the owners manual for your car?
Also, in addition to a transmission fuse, there is a fairly vital transmission relay. On my car it is buried under the glovebox. On your car, I think it might be under the hood. It should be the one with the purple base. I would confirm that, though; because they made changes between the model years and I'd hate to give you bad advise. If you are still dealing with transmission faults, this is a cheap thing to eliminate. Relays are about 12 dollars from one of the suppliers.
Do let us know how you are getting on. I'm especially interested to see how you and/or your mechanic get the transmission fault dealt with. Best of luck! Scott

 

Thanks a bunch! There is a relay with a purple base, and that's the one getting hot!

I have all Hella relays, btw. I don't have the owners manual, but I did replace all the bad fuses in the passenger floor block. I thought about getting a Hayne's manual, but I've found over the years (being mainly a Mustang/Pro-Street guy) after working on NUMEROUS vehicles, that Hayne's manuals are a joke.