I am 100% correct about the operation of that circuit. It the ground to pin 2 is good, and it is getting power on pin 3, and the other pins are at about 12 volts do not change state when the switch steps through the positions, the switch is bad.

The fuel pump code has nothing to do with the pump motors. It is a monitor for the fuel pump #1 relay coil circuit. Look at the diagram. There is absolutely no way the module can determine whether the pump motor is running. Why would it give a fault for no pump relay circuit current? Assuming the ECU is good, then either power from the circuit I identified in post #37 is not there or something else is amiss. I know you checked the fuses, but I think that may have been before the latest symptoms. Note, at least some of the other things you say are not working are also powered from that cicuit.

Also, the linear switch connects to the ECM section marked "fuel pump control..." The diagram does not show the internals, but it is quite possible if that circuit is not as expected, it might interrupt the relay coil and throw P1230.

Good luck.

 

I heavily agree with this. I've been down this path before many times with customers cars, especially the X300/308s. Even after I've cleaned and tightened all the power and ground junctions, only some of the gremlins went away. Most of the time the contacts in the square brown relays located everywhere in these cars are either burnt already, (because a lot of them provide power for the fuse box) or on their way out. Realistically, these are pretty good relays with the exception that they have a lot of current flowing thru the contacts and need to be kept clean or just replaced with a high quality one. They're just like old ignition points that I used to deal with on my old 66' Karmann Ghia. Especially in these finicky aging Jaguar cars, If you don't have a very healthy battery, good clean power, ground or contact for electricity to flow thru, you'll get back feed, intermittent issues and eventually component failure. When I get one of these cars in under these same circumstances, I disconnect the battery and discharge the power from the car, check and clean all power and ground junctions, I pull every relay out, open them up and either clean the contacts with a small flathead if they aren't too bad or I replace them. 95% of the time the problem is fixed. I would perform this as a maintenance function and to perhaps help you in your situation.

 

I only mentioned the pumps because at least one person had mentioned it could be bad fuel pump(s), not that I thought the car could tell if it was running. the signal(s) it wanted to trigger the relay that controls the fuel pump(s).

 

Thanks. I did swap the primary fuel pump relay with another in the box with no change. I’m sure it wouldn’t hurt to cleant the relay contacts; I’ve just never had a reason to suspect them. I’ve had my 1991 300ZX since 1997 and it has 250k miles and I’ve never had a bad relay, nor do I recall readings posts on my Z forum about bad relays.

Definitely worth checking though.

Mike

 

You can simply test the voltages with your meter. That will tell you myriad number of things!

 

I understand exactly what you mean about the reliable relays on other makes/models. You can pretty much throw that theory out the window concerning Jags. I have never come across so many bad relays in my 22 year career as a technician than I have when I started on Jags about 4 years ago. Probably in the first 3 months of my 4 years with Jags now, I've replaced more bad relays than I have in my previous 18 years with GM, Mitsubishi and Toyota combined.

 

May have found the problem.

I had removed the rear seats to get the rear deck cover out and to do that I had to pull the heelboard fusebox covers. I had left them off. The “ignition positive relay” was almost falling out of its socket. That explains why the car ran fine until I picked up my kids; when they got in the car they kicked the relay to the point it was loose enough to lose contact with the pin(s) in the socket…….

Seated the relay and turned the key to “ON” and all the dash warning lights came on as they should, AC panel came to life and blower turned on. Cranked engine and it fired to life.

I do have a “restricted performance” warning now, which I did not have before. Going to get the car back together enough to drive, clear the codes, etc and take a spin around the neighborhood.

Fingers crossed.

Mike

 

Somehow, I feel vindicated.

Glad to hear it.

 

Mike:
Thanks for posting back with the results. Now you can fix the lambda sensor and start chasing codes.
Like Jim, I feel compelled to remind you that you would have found that back pinning the ECU pins with the meter. And, Google Occums's Razor.

 

Jhartz/sparkenzap,

Yup, once I went back to basics and started tracing the circuits I found it. Started checking for voltage at ignition, fuel injection, and fuel pump relays. Jumpered the fuel pumps to ensure they ran with +12V. Then started looking at why the shifter had no power and started troubleshooting the left hand heelboard and the loose relay jumped out at me.

I have to say, I never wanted to become as familiar with the circuits of this car as I have had to. And it does throw some crazy error codes…. Earlier in the week when the battery voltage had dropped from the crazy red light flickering on the shifter console I got a new error “washer fluid low”, and apparently that means “battery voltage low” on this car. Who would believe it?

I have a host of other issues to resolve once it warms up:

A couple weeks ago the outside left rear passenger door handle “broke”. It flops around with zero resistance and the door can only be opened from inside.

The J-gate backlighting has never worked that I remember, I didn’t even know it was supposed to until I started researching on this latest adventure.

The steering wheel defaults to a position that is too low everytime I unlock the car even though I have let it learn/resynched it half a dozen times.

The sunroof rattles like crazy and I have to wedge a piece of cardboard up there to stop it driving me crazy. Haven’t used the sunroof in a couple years for fear it will open and get jammed/be unable to close.

Have new bushings and ball joints for lower control arms. Had my friend weld me up a tool for lowering the arms. I have a press and bought one junk control arm so far to rebuild so I can do a one-for-one swap and minimize my downtime.

I need to replace the rear shocks as they are definitely worn. I installed XJR non-CATS dampers up front a couple years ago and the transformation was fantastic. I had a friend machine me some adapters to use in the existing upper mounts as the CATS shafts are 12mm and the non-CATS were 10mm.

Valve cover gaskets are leaking.

Oh and the clearcoat on the trunk has started to peel off in large areas. Starting to spread to the tops of the rear fenders now also, grrrr…..

Thanks for the help on my current issue, and I apologize if I came off as an *******. Not my intention.

Mike

 

Three principles, all the same: KISS; for army guys, High diddle, diddle, right down the middle; or Occam's razor.

An old Hudson mechanic who used to drive cars with my Dad into Piitsburgh from Detroit gave me my first summer job: changing oil and tuneups. gave me two rules of auto repair (one which I have seen repeated on this forum): patience is the best tool in your toolbox; after you fixed it, if it doesn't work, you probably did something wrong.

I remember tuning a BMW 325IS once and when I was done I had a check engine light: panicky I queried a phone line BMW technical service. The guy answering the phone asked if I put the air cleaner box on the ground in the sunshine, I had. He said the sensor gotten over heated, probably ok now. Sometimes, you have to simply use the simple solutions.

Let us know how changing the lambda sensor goes; my next project since Abacus isn't answering the phone. Found the best price for the Bosch unit on Amazon ($66).

 

Mike, other than the CATS, your's sounds about like my 2 XFRs. But boy is it a fun car to drive. When right, I like an XJR better than the newer big cat!