Hello all!

I have a 1995 jaguar vanden plas, I hope I am posting in the right place. This car will not start. It turns over, fuel rail is pressurized has a brand new battery and every fuse and relay in the entire car has been checked for resistance. the check engine light is on and when I pluged in my odb II code reader it read P0335. this is for a crank position sensor. I went to a junk yard, bought a new one and the car started and drove like new....for an hour. when I tried to start it later THE SAME DAY!! it did the same thing it did before i changed the crank position sensor. I checked the new sensor I got and it passed all tests. it read 1300 resistance and 250 mv on an oscilloscope. I am not getting any spark from my brand new spark plugs but I have read that if the ECU reads the crank position sensor is faulty, it will halt the ignition/injection process. I am really stumped and getting very frustrated at this beautiful/demon possessed car. any advice would be greatly appreciated.

Thanks,

Andrew

 

Another thing I forgot to add, after purchasing the used crank position sensor (that made the car run for an hour or so) I went out and bought a brand new OEM lucas part. the check engine light stayed illuminated on the dash but my obdII reader could not find any codes. I also borrowed my neighbor's obdII reader, to be sure mine wasnt messed up, and had the same result. The car cranks, is getting fuel, check engine light is on with no codes on an obdII reader, and it refuses to start.

Thanks,

Andrew

 

Have you tried wiggling the wires at the connector for the crank sensor? They can become loose and lose signal, leading to the code and a no start.

 

Any turns on the rev counter while cranking?

 

Thanks for the replies!!
I have tried moving the wires around at the connecting point on the sensor, but still no dice unfortunately. Also the tachometer reads 200-300 rpms while cranking.

 

A friend of mine that is big into porsches and bmws said it could be a faulty ecu.... I hope thats not it. is there anyway to test something like that?

 

There have been a number of reports recently of water ingress to the ECU wiring and causing corrosion to the connectors. The water likely comes from a deteriorating sunroof drain tube "conveniently" located above the ECU. ECUs themselves rarely fail on these cars.

If it is not that, then I would take a close look at what I could heve buggered while changing the CKPS. Check the spark coils for power and the injectord for pulses using a noid light. You probably ought to start figuring which of your nerdy friends owns an oscilloscope

 

Hi Andrew,

Since your tach reading of 200-300rpm would seem to indicate that the ECM likes the signal from the CKPS, here are a few more possibilities:

Check for 12V at any coil connector with the key in position II. All six coils receive a constant 12V from a relay which I think I recall is in the front right corner of the engine bay. That relay is known to become intermittent as it fails, and corrosion in the relay socket base is also common. Perhaps you bumped the relay while you were installing the second CKPS and caused it to work again briefly.

Also, it would be worth cleaning the ground studs the ECM uses, which I believe include a couple on the bulkhead and maybe one on the front inner fender/wing - check the schematic in the Electrical Guide, which is available for download from the X300 'HOW TO' quick links thread at the top of the home page of this X300 forum. If that link is dead, send me your email address via PM and I'll send you the manual in pdf form. Looseness or corrosion (even hardly visible corrosion) on the wire connectors, wire ring or eyelet terminals, washers and nuts of ground points add resistance that can cause difficult-to-diagnose gremlins.

One more possibility: even with a new battery, if the voltage at the ECM drops somewhere below 11V while cranking (due to looseness or corrosion on the battery power connections throughout the car), it will not trigger the ignition to fire. The Electrical Guide shows where all the battery power connections are - I think there are 3 on the bulkhead, one at each fuse box, one each at the alternator and starter, and maybe one or two more rearward toward the battery. Cleaning the battery terminals and the battery ground point on the body would be worthwhile also.

Cheers,

Don

 

I would swap ecu relay out with another nearby, ecu relay common problem. Also the crank sensor has a relay, another common problem..

 

"Also the crank sensor has a relay"
REALLY?

 

My understanding is that the relay for the crank sensor is located in the passengers side fuse box, it is the blue relay and it stands out from all the others. Pretty sure this is true unless I completely lost my mind.

 

Hi jeremiahjaguar,

Figure 04.1 of the X300 Electrical Guide clearly shows that the two signal wires of the CKPS connect directly to pins at the ECM, and the cable shield connects to ground. There is no relay in the circuit. But no worries, I lose my mind at least once a week!

Cheers,

Don

 

Thanks everyone for all the information and suggestions! I will try cleaning ground points and check that there are 12v at coils. I have checked all relays and there is no corrosion. They are actually quite shiny I will also check the ckps ground and connection to ecm. I just dont understand why, if there is any fault in the circuit, the crank sensor would still read 200-300 rpm on the tachometer. I believe the blue relay in the passenger side engine bay fuse box is the engine management relay. If im not mistaken.

 

Where is the ecu that would give me a problem with the ckps. I know there about a million ecu modules in this car...