Hi everyone,

I'm trying to get stuck into a long standing issue with my UK based 1997 XK8 (104,000)
It's been off the road for 18 months with a power but no crank issue.

I'm now concentrating on the throttle body for the reasons below, I'll also include a list of other things I've looked at.

So the car powers up but no crank at all.
With the key turned to position 1 I can hear the butterfly valve in the throttle body click and then there's a permanent buzzing which I can feel vibrating in the TB.
I removed the air intake and cleaned the valve, it all looks good in there. I replaced the intake hose but it was exactly the same.
I removed the hose again and watched the valve when I powered it up. The valve literally moves a couple of mm and the buzzing continues.

I'm guessing there's a servo that operates the valve, could this be faulty which is causing the buzz?
Would this actually prevent an attempt to crank?

The other things I've looked into are.
Replaced battery with new
Replaced battery leads
Checked ground connections (front and rear)
Checked HPP connections
Used both keys
Checked the ignition safety cut off
Disconnected the intelligent sounder in case of fault
Checked fuses
Swapped starter solenoid relay

I'm aware there could be other issues but I'm sure the throttle body buzzing isn't right so concentrating on that for now.

Any help or advice is greatly appreciated

Many thanks,

Rich

 

Failing to crank has zero to do with the TB.

Do you have / have you had any DTCs (codes)?

 

+1 to JagV8,

Rich - you have a no start issue. Could be anything, so first thing to do is to get any DTC codes from the OBD2 port, otherwise you're "shooting in the dark." Could be a zero dollar fix, or a more expensive/complex reason from bad starter to ECU trouble.

Any cheap OBD reader would give you a heads up, (beg,steal or borrow) but if you're keeping the X100 for a long time, you'll need a specific reader for the car to get in depth ACCURATE DTC codes. Lots of info on that here on the Forum (just use the Search function).

 

AFAIK , the throttle body buzzing is normal.

 

Thanks for the advice so far gents, I've purchased a reader that had been successful for another forum contributor but it didn't pull any codes out for me.
I've ordered another one that claims to be JLR specific so we'll see how that pans out once it arrives.

 

throttle buzzing is normal.

start with the basics, if you move the gearshift with your foot off the brake in position 1 do you hear the chimey alarm? That’s the park position micro switch, if it’s wonky have tried starting in neutral?
If your rotary switch is working on the transmission, you’ll get no messages, I’d not you’ll get a yellow alert and an ‘engine fault’ message. The BCM does the cranking in 1997 I believe.

 

Yes I get the alarm if trying to move the gearshift.
It won't crank in neutral.
The system check message appears and then goes off as it should.
The yellow check engine light is on below the rev counter but again I think that's correct as it would go off after start up.

 

Will it start in neutral?

 

no, it doesn't turn over in any shifter position.

 

http://www.jagrepair.com/images/Auto.../jagxk1997.pdf

I guess start by looking at the wiring diagram, you could check the signals to the starter relay, etc.

 

Look at this, if you’ve got no codes start with checking the starter relay, if you haven’t already checked the battery negative terminal is clean
http://www.jagrepair.com/images/TSB/...rd%20Start.pdf

 

So the code reader arrived and to my surprise actually pulled some codes out. I ordered the iCarsoft i930 but they sent me the LR V1.0 claiming its a free upgrade to a better machine.

I'll list all of the codes in case they have a common denominator but I'm hopeful that the first 2 in particular could lead to something definitive.

Module Code Description
Body Processor Module B1352 Key in circuit failure
Body Processor Module B1595 Ignition switch illegal input
Body Processor Module U2012 Communication bus error - non SCP
Body Processor Module B1794 Headlight switch active with sidelight switch inactive
Body Processor Module B1446 Wiper park sensor circuit failure
Body Processor Module B2368 Column adjust switch out of range
Body Processor Module B1450 Wash / wipe switch circuit failure
Body Processor Module B1875 Turn signal switch left + right active switches
Passenger Seat Module U1135 Ignition state not obtained
Passenger Door Module U1041 SCP vehicle speed signal invalid or missing

Any thoughts on those at all please?

 

Well, a lot of these point to the Body processor module not seeing ignition switch and not communicating with the instrument pack, if those are 1997 codes, I can’t find the 1997 list right this second. Could anything have happened to the wiring to the ignition switch since you last drove it? I’m pretty sure that 1997 don’t have a key transponder, so either somethings up with the BPM or instrument pack it seems. Did the car get wet/ humid? I had similar instrument pack codes when my car sat up with the windows cracked and got damp inside. Once the instrument pack dried out it started acting right.

 

Have you tried sitting in the car and enabling and disabling the alarm a couple times with the Fob? Maybe the car thinks it’s locked and the keys have been inserted?

 

Thanks for your replies Stephjac, it was working fine, left it for 3 weeks and the battery was dead. Had it tested to confirm it was dead so bought a new one.
I've had this problem ever since. (18 months ago)
I've tried the fob from inside the car multiple times and it hasn't got wet other than a bit of condensation, nothing major though before or after the issue arose as I air it regularly.
I know it could still be lots of things but investigating the BPM seems like the next sensible action.

 

Hello, If you decide to remove the body control module, I suggest you consider removing the battery ground lead and touching it to the positive post first. That is supposed to drain the capacitors on the logic cards. Check with the experts on the forum before doing this. Once the module is accessed, view the capacitors (usually brown tube like items). If any are swollen or discolored they will probably be failing. It is possible to replace them if you have good soldering skills. Messing with the control modules is always a delicate activity. The battery must be disconnected during the whole procedure. Please don't go ahead with this without researching the steps. Bad capacitors can cause false DTC codes.

 

What's a BCM

 

You know what I would do is manually start the car by connecting a jumper cable straight to the Bendix and starter motor, ignition on on and if the car starts let it run op to temperature shut it of and try to start with the key, it might erase all the gremlins, good luck.

 

I don’t have the diagram in front of me, but first I’d check that you have the voltage at the starter relay, then work backwards form there in the wiring diagram, get a meter with needle probes that will slip inside the connectors and it goes faster, ruling out the ignition switch would be a help. You could have a blown fuse in the trunk, that would disable the starter. My issues started when I tried to use the car starter function on a battery charger, it caused my instrument cluster to shut down for a week. If you tried to jump start the car with a jump pack or anything like that you may consider having the modules scanned and reprogrammed as needed. Strangely my ICM started to slowly come back to life over the course of a week, so I lucked out.

 

BCM=body control module=BPM= body processor module