Was driving on 70, when looked down on the instrument cluster and saw all the instruments off and engine was dead. I pulled over and tried to restart. No lights, no crank. Windows and sunroof were operational, radio, wipers and all instrumentation were not..

Here's what I got so far.

1. It's not inertial switch. (Pressed down)

2. Battery is ok, alternator belt on.

3. All fuses ok.

Any help greatly appreciated, my mechanic is looking to me for answers. Thanks.

 

That's just disheartening Mad Russian.

Hopefully it's something basic. Feul pump, distributor (vcm?), cam position sensor or does it have crankshaft position sensor.

 

Mad_Russian,

So sorry to hear about your difficulty.

Since all fuses are OK in all three fuse boxes, without looking at the schematic to determine which of these involves all the circuits affected, my first suspects might include (in no particular order):

A critical relay such as the EMS relay or Ignition On relay, either failure of the relay or corrosion in the relay socket

Water ingress of the ECM or CPU or corrosion on their connector pins (the CPU controls wiper logic, power windows and locks, some or all lighting, and other things)

Maybe a problem with the power supply or ground to the Instrument Cluster(which communicates with the CPU, ECM, TCM, ABS Module and other components)?

Cold solder joint(s) in one or more of the fuse boxes


I'll try to think of more. Please keep us informed.

Cheers,

Don

 

Don, thank you so much for the info. I was suspecting a relay failure. Could you tell me where the EMS and ignition on relays are located please? I have another 93 I can pull parts from if needed. Just need to know locations. Thank you.

 

Hi Mad_Russian,

The relay locations are shown on pdf page 10 of the '93-'94 Electrical Guide which can be downloaded at this link:

http://www.jagrepair.com/images/Auto...ec%20Guide.pdf


Cheers,

Don

 

Another possibility is the security system controller. Have you changed or disconnected the battery recently?

 

Gentlemen, I was able to get the car started by bypassing the "ignition on" relay with a simple switch (in case anyone ever has to get to theirs, is on the right side of the radio inside the center console). I still don't have the radio, auxiliary power and my cigarette lighter doesn't work. Relay was not getting any power from the key rotation, other than main ignition circuit current, which leads me to believe at this point that I might have a failed ignition switch, and there's nothing wrong with any of the relays. (I swapped them around without any changes).

My question is, could I just bypass the ignition switch all together for the auxiliary power relay, and just mount a switch on the dash? It would basically involve figuring out which of the wires from the ignition switch controls it and send the power directly to to it.

Many thanks to Don for the info on the relay locations and possible causes.

 

Hi Mad_Russian,

Good diagnostic work!

I do think it would be possible to bypass the ignition switch for those circuits, but the ignition switch is still available from Jaguar Merriam for $77.78:

https://www.jaguarmerriamparts.com/p...&siteid=215718


And replacing the switch is not difficult:

Welcome to Jag-lovers - Members Photo Viewing Page


The switch mounts on the end of the key barrel, so you don't have to change keys.

I haven't tried to disassemble a malfunctioning ignition switch to see if it could be cleaned and repaired, but if you're so inclined it just might be possible.

Cheers,

Don

 

Mystery deepens... I checked the ignition switch, and it appears to be working fine - all the contacts close correctly. I also did a continuity check between to make sure it wasnt' the constant up and down adjustment of the steering wheel that wore the wires out, and wires are in working order.

Question --- the AUX wire from igntion switch (White with Brown stripe). Does it simply close the ground, or does it send 12v down the wire to energize the AUX power / radio relays?

Thanks.

 

Hi Mad_Russian,

Check the schematic for Ignition Switched Ground in the Electrical Guide to confirm this, but off the top of my head I believe the ignition switch connects all the circuits to ground, it does not "supply" 12V to any circuit.

Cheers,

Don

 

Don, I will see if i can override the AUX wire with a "to-ground" switch. Thank you for the info.

 

Update.

After my highway incident, my radio, cigarette lighters, and high beams didn't work. I checked the fuses and found the "fuse failure link" to be blown in the driver side fuse bank. It was missed the first time by me and the mechanic both. Once the fuse was replaced, everything started working again. It also restored my ignition relay functionality.

So just as a word of caution, when you start having issues with the car, make sure all the fuses are ok. And use the tester - mine looked fine, but was burned out.