The beast ('01 XJR drivetrain in a Mark 2) was running great until - Restricted Performance popped up and AC compressor went offline - everything else was fine. Next time I drove the car it banged in and out of gear and wouldn't shift out of 1st. Also Trac Not Available and ASC Not Available plus the following DTCs - 1671 Secondary Fuel Pump Relay, 1720 Vehicle Speed (Meter) Circuit, and 1165 and 1175 left and right rear speed sensors. A couple of hard resets had not effect. Appreciate any thoughts as to where to begin.

 

Rear loom seems to be offline, have you looked at the connectors, under rear seat for the link leads to the wheels speed sensors etc

 

I can't help but is there a build thread for such an interesting sounding beast?

 

When you cleared all those codes, were any of them hard faults?

I believe the right rear wheel speed sensor is what drives the speedometer and can put it in restricted performance if that stops sending a signal. Even though the codes are for both rear wheel speed sensors, you could swap both rear sensors side to side as a quick test. As a secondary test, you could also ohm out both sensors and compare readings.

 

Thanks for the suggestions. I exercised all of the rear harness plugs including those at the sensors - everything was clean and intact. Addicted - I don't know what a hard fault is - if it's one that the code reader won't clear that's what I've got:0) I'll swap the sensors and check ohm readings - will let you know what I find. Hooli, there's a long thread (XJR Mark 2) covering the build in the Mark 2 site.

 

Ta for the guide to the build thread, I'll have a look for it.

 

Both rear sensors read infinity/open circuit. Wasn't sure if that was normal so read voltage when exciting with a screwdriver - got similar readings for both sensors - millivolts I think - but too inconsistent with a digital meter to record anything meaningful. Conclusion is I think the sensors are fine. Any thoughts on where to go from here appreciated.

 

No replies so I went to check the abs system as a possible cause of the problem. Now the beast won't even turn over, new items appearing on the dash display include gearbox fault, failsafe engine mode, low brake fluid and incorrect part fitted, and I'm unable to even connect to the obd system. Anyone care to guess which if any of these might relate to an actual problem? I'm about to torch the beast.

 

Usually a bad battery / bad power.

 

Battery is recent and kept on a tender - reading 12.9 volts. Pretty sure that's not the problem but I don't have a load tester so will swap with my wife's XJR battery to be certain. Thanks for the thought.

 

The 'scroll of death' I've experienced, if I remember it was something to do with the transmission alignment of the selector - cable - and gear surround electronics. Maybe look around this area for anything out of wack, and a possible reset of the gear selector alignment.
Try a hard reset to clear the clutter, and see what codes you get too.

 

The large number of meaningless codes and then the inability to even connect to the obd system suggested I had a connectivity problem, and sure enough we found a big one. As I began pulling down underdash harnesses to check connections I came up with this one - the main bulkhead plug that feeds the engine compartment. The locking mechanism must have snapped the last time I made up the connection and it gradually worked itself loose. I went searching for a universal firewall connector (I counted 34 wires) and everything I found poses a clearance issue with the pedal housing in the engine compartment. If anyone has a connector/derelict harness available or knows a source please let me know, and thanks again to the folks who tried to assist on this one.

 

Just a thought..Is there any way you can drill a couple of small holes above and below the connector through the bulkhead area and put a zip tie around to hold it in place?

 

Good thought - unfortunately access is tight on the engine side and virtually non-existent on the inside, plus the plug is watertight and I'd like to maintain that. A local Jag specialist has a parts car he's willing to let me liberate a plug from - not sure if the individual wires/sockets can be removed from the old plug and inserted into the new one, or if I'll need to cut and solder a bunch of wires (this is the female side of the connector).

 

you should be able to de-pin the connector with the right tool. dont try and use weird flattened paper clips or things like that it will just be difficult and frustrating. ask me how i know...

 

Thanks for the tip on the depinning tools - I didn't know they existed. I bought a cheap set (23 I think) of various sizes/types as I noticed there were a few different size terminals and wire gauges in the connector. The tools made quick work of it - about a minute to depin the donor plug and about a half hour to transfer the pins one at a time. The beast fired right up and I cleared the numerous codes with no issues. The locking arm is not quite fully home and I don't want to force it (I think that's how the last one broke) - I suspect my firewall insulation is preventing the connector from fully seating, so I'll remove that around the opening and hopefully we're done with this episode.