1993 XJ6 Vanden Plas . Car runs well and on occasion will die without warning. When I pull the "Fuse Failure Link" fuse located on the left side (drivers side for U.S.), fuse location is A3 with a 3 amp fuse and reinstall it, the car restarts with no problem. The fuse is not blown. Just pulling it and reinstalling it takes care of whatever is being "reset".

 

What does the VCM fail code show before the reset?

Larry

 

Larry,
It's showing "Fuel Fail 44"

 

Should I replace the O2 sensor?

 

[xj40] Fuel Fail 44 - XJ40 - Jag-lovers Forums

A quick and cheap and easy thing you can try is to jumper the fuel pu.mp relay between socket 30 and 87

The pump will run at all times with the keys in your pocket so plan accordingly

preferred to use blade type connectors in the fuel pump relay socket

The auto parts store can help you make a jumper with the behind the counter tool kit and heavy wire

 

Thank you!

 

Edited above post for more info

 

FF44 circuit failure will not prevent engine running, it will just keep the car in open loop operation, so you'll have less power, run rich/use more gas.

Check for a vacuum leak or bad connections before assuming O2 sensor has failed.

Using a meter there is a test to determine the condition of the oxygen sensor, search the forum for details.

Larry

 

See page 91 of the 1991 wiring guide file below

File link below

Jaguar XJ40 Electrical Guide 1991

A note on the O 2 sensors which play a major role in the closed loop mode of the ECU

Is how it gets from the open loop on cold engine start to close loop triggered by the coolant temp sensor using the O2 sensors for a just right fuel mixture

This trigger point is 88 C for the later refined AJ16 engine from your AJ6 engine so yours is probably the same value

Some things that can keep the ECU from seeing the 88 C is a dirty temp senspr connector, temp sensor itself ,or the actual coolant temp never gets to 88 C , coolant thermostat failed open

The temp gauge on the instrument cluster is a separate temp sensor not related the the one triggering you ECU open / close loop

Your instrument cluster is on page 31

Verifying

True , the instrument temp sensor ( transmitter ) is single wire and the ECU temp sensor is 2 wire so they are separate

But it can be used as a reference to know where your coolant temp is at

Donel editing

 

See page 181 and 183 of the Jaguar 801s PDF below

This document is in 3 sections : the later AJ16 . your AJ6 , and the V12

801S TITLE (jagrepair.com)

You can compare the temp sensor with a meter against the chart

 

Welcome to the forums Paul,

That's a very strange thread title. Did you intend to post in an existing thread? If so you must have clipped some of the string because it doesn't find a thread.

Graham

 

I copied and pasted it from another thread that I miss posted to the wrong model group thread and that's how it "pasted". It was originally posted as just "Electrical issue". I couldn't find anywhere that I could've edited the title.

 

Will do.
Thank you.