Diagnosing some issues on this 2001 XKR. Running fine, OBD codes of low power to both o2 sensor heaters. decided to check the fuses for the heaters and relays. Pulled fuses... fuses fine. Put fuses back in. Now car will not start, with FAILSAFE MODE / INCORRECT PART FITTED displayed. Tried disconnecting battery cable, draining. Feeling a bit gutted right now as I have just put significant $$ in the transmission and front end. I suspect that there's a wiring issue near the area of this fuse block. Anyone else run into this? Any suggestions?

 

Wait, did I just solve my own problem, with a smoking gun diagnosis of a bad fuse block which would cause both a 0mV and a 0.005mV OBD real time reading on the o2 heaters, and when I pulled the fuses, I jostled the fuse block enough to cause a loss of power or ground across the circuits to the ECU? Or am I smoking something strong? Or should I?

 

Yes and yes…..


Z

 

Best of luck escaping NE Oklahoma. Grew up there. There aren't many road signs that direct people out of the state.

 

i grew up here, then left and hit most of the known world. Now in retirement so have made the move back, making the circle complete.

I do prefer these wide open spaces. There’s more people in DFW than in the whole state of Oklahoma.


Z

 

Well. Today has been a little revelatory but we're not 100% sure my hypothesis is correct until the new 18-way fuse block comes in... but let me show you around today's discoveries. First, when I pulled off the relay cover, the relay was stuck in the housing and no way was it in its intended home. That's figure one. But that's not all!

This 18-way fuse box is a bit tragic. obviously someone has been in here who, I believe the British parlance is an "absolute plonker". Figure two shows a ground strap to this fuse box (I'm pretty sure that's ground anyway, that was massively overtorqued. Nothing really holds that ground to the fuse block other than a tack solder on the underside... and it looks like one must take care to get a wrench on the backside keeper nut and a 13mm on the front to safely remove the lead. This care was obviously not applied, as this bolt was tightened to a level in keeping with suspension bridge construction. Hence, the lead into the fuse block's circuit board was wibbly-wobbly. That, I assume, is not by design. This in conjunction with a cracked housing is more evidence of the existence of our anonymous hamfisted oaf under this hood.

The brittle nature of all this wiring concerns me, but, one thing at a time. I've got a new fuse block on order (well... new/used/salvage) and will let you all know if this solves the maladies of the 1400 or so individual items that are fused at this junction, including my aforementioned unpowered O2 sensor heaters.

 

Update: Installed new fuse box, resecured ground. Replaced all weird random relay brands with known-good brand 4-pin relays. Result: Only remaining codes were MAP sensor and P1000... MAP sensor code seems to have gone away after reset. Catalysts are catalyzing, O2 sensors seemingly normal values, but I'll feel better after a drive cycle (P1000).

I'm onto now what sounds like timing chain noise. nothing hard knocking like a spun bearing, but a little tick upon starting and then after it gets hot. Sounds like lifter noise, but will get random clacks at idle. GUIDE STATUS UNKNOWN. I wish I had a good line on a Jag engine specialist in Denver... the shop I had do the transmission and front end work didn't seem to even know the guides on these X100 engines were even an issue (!). Of course they also said I needed new catalytics and O2 sensors and didn't even check the relays, so I'm not super confident in their perspicacity.

Any Denver area folks, HMU with engine shop recommendations.

 

If you can pull both valve covers off, a little goes a long way by looking at the secondary timing chain tensioners if they are the original plastic brown ones. If you don’t know, I would not start the engine again as it’ll really send that car’s future sideways.

 

If @2500DollarXKR is indicative of price paid for the car, then spending $10,000 on it to bring it up to roadworthiness is not money wasted.

Sorry not to be any help with the CAT codes, but as far as the changing the tensioners goes, just do it. Lots of good how-to info on this site that should give you confidence to do it yourself.

@Addicted2boost has it nailed. Just don’t even think about starting the engine until a determination has been made regarding which tensioner version is in place. Better to be safe than sorry.

The previous owner of my 2002 XKR landed in the “sorry” group @ 116,000 miles.



Z

 

There is no ground strap to the fusebox(es). That is the main +12V from battery!

 

It's definitely next on the list to address- hopefully I can find a competent shop in the area to assist. No sense throwing money into other parts until I stabilize and make the engine a known entity.

 

Yes! I determined that with the multimeter (thankfully) before I did anything else). I did tighten up all the connectors though. THAT part is relatively stabilized. Onto the engine.

 

The secondary tensioners aren't all that difficult. Some basic hand tools and some sturdy zip ties are all you need. Just pull the RH valve cover off (it's the easiest one) and check. If the RH one is OK, the left one will be too.