Good day every one, I am new here hope to get some technical advice here . I own xj6 3.2 engine 1995 model, 230k mileage. It suddenly refused to start. No current to the plugs, starter kick, fuel pump and dashboard. I have replaced the dashboard processing unit, the brainbox and the body processing unit yet no sign of current. All the fuss and relays have been checked. Please I need a helpful advice.

 

Welcome to the forum. You will need to go here: https://www.jaguarforums.com/forum/n...-intro-must-5/
and make an introduction for a proper welcome aboard and begin your journey toward full membership benefits.

I know, I know....you just have a problem you want solved. Others will be along presently to offer helpful advice. For now, I'm still quite puzzled as to what the discrepancy is. I'm equally confused as to what components and modules you have replaced and why?

So far, I gather you got in the car one day and had no electrical power anywhere...as if someone nicked your battery. Yet you make no mention of checking the battery voltage and condition nor any discussion of checking the connections between it and the car?

Just trying to interpret your replaced items: Instrument panel, body processor module, and ECM(brainbox?)

Search for "Gentlemen (no) start your engines" thread started by myself for insight into the problems others have encountered that have prevented successful starts. I really don't recall the IP nor body processor module being a culprit. ECM is occasionally mentioned, but usually only due to corrosion on the connector pins.
Good luck!

 

It's too easy to install the battery in backwards with a top post configuration . This will drive the car and yourself nuts . I did it myself . all is not lost as I'll walk you through the steps to bring it back alive . Some things will be knocked out so just correcting the battery polarity won't bring her back yet as I'll go though them as they are easy and cheap DIY fixes.

Make sure that you have the positive post in the positive direction of the car or positive toward front .

It could also be that you have a bad battery as undervoltge or a open cell . It could also be that you blew the fuses that I circled in the below wiring schematic . The single 250 mp fuse is I believe under the rear seat as you pull the lower seat up but we'll do the easy things first before looking at that . Do you have power at the terminal post of the trunks fuse box ? ( circled in blue )

When I did it to mine I knocked out the instrument panel , alternator voltage regulator ( part # IN435 / 25 dollors ) , radio and others

OEM DENSO VOLTAGE REGULATOR REPLACES 126000-1200, 8970320910, JLM-11144 IN435 | eBay

Editting post

 

G'day King,

At the base of the rear seats, on each side, is what Jag call a heel board fuse box. In each of these is a blue relay which if they malfunction will cause the car to act dead. These relays should click when the ignition is turned on, if they don't then that's where your problem lies. You'll need to take the covers off the fuse boxes to hear the click.

The covers are retained by a single, central phillips head screw, take off the covers on both sides and remove and replace the relays, that might fix it. A dodgy connection can sometimes be the problem. If not go to an autoparts place with one of the blue relays and but a couple of spare ones and try them.

Cheers,
Jeff.

 

https://www.jaguarclassicparts.com/u.../relays/relays