Ok, on my 2000 s-type with a 4.0, I just finished rebuilding the motor. I got the motor and transmission in and primed the engine with oil. I went to start it and found I am not getting fuel or spark. I am not getting voltage to the coil terminals of the fuel pump relay. I am suspecting the pcm may be bad, is there a procedure to test it? Also, the owners manual gives you a layout of the fuses but not the relays and the JTIS manual is about worthless also. Is there any reference to the relay layout, I THINK i am testing at the fuel pump relay because I found a crappy pic that indicates it as the fuel pump relay. Also, I lost my full wiring diagram so I can't trace any wires.

BTW, I did replace the crank sensor and nothing changed.

Thank you for your time,
Ryan

 

how long did it take you to rebuild your motor?

 

Quite a long time, about 16 months! I just never had time to work on it and I have other cars to work on.

I was wondering if the length of time it sat without a battery could be a cause?

Also, last night I went through every accessory, light etc... on the car to see if there are mulyiple problems and I did notice a strange one, when the ky is shut off and removed, the steering wheel does not lock in position? IDK if it's unrelated, it just seemed strange.

 

I've not looked for the 2000 model, but the electrical PDFs look to have all the details you ask for. I believe they're part of jtis and also on the net if you look.

Generally, PCMs don't seem to fail. Obviously yours could be the exception but I'd check it last.

 

Ok, I paid for that GTR jaguar tech program and pulled up the schematics.

It is still difficult to follow (my old ones clearly labeled supply voltage to the pcm, this one doesn't) I checked the two pins it said supplied the pcm with voltage and measured 12.12 volts with the key on.

I did some more diagnosing and pulled the fuel pump relay (I now know for sure it is the fuel pump relay!) and checked the voltage on the hot terminal and found it to have 12 volts. I then ran a jumper wire from that terminal to the switched terminal (i believe it's terminal 3 on a micro relay) and the fuel pump still did not run. I looked at the diagram and found the fuel pump is PWM so I'm guessing the PCM is not closing the transistor to give the pump a ground. I just got done going through EVERY relay and EVERY fuse on the car and everything is good.

Every test I do comes back to the pcm being bad. The pcm controls the the control side of the fuel pump relay, there is no voltage there. The pcm controls the ground side of the pump, when voltage is applied to the positive, nothing happens.

I just really wish there was a way to test the pcm so I know for sure it is bad. I really don't understand how the pcm could go bad just sitting in the car for over a year, no voltage going through it. We didn't have ANY problems with the car prior to the engine blowing up. However, the mechanic that ripped us off may have fried it.

Thanks guys, keep the suggestions coming!

 

I am not a tech or anything but did you check the inertia switch? Doesn't that kill fuel pump and electrical...

 

Inertia switch isn't tripped. Also, that only cuts off the fuel supply, not ignition.

 

I don't know if you've dealt with a local dealer. Some are not as "money" driven as some would believe. It's hit or miss, but they may be able to test it for you for just a small fee. It wouldn't hurt to ask.

 

Can you OBD the PCM? It may well tell you what it thinks is wrong.

Er, don't you have the MIL on? It sounds rather like you should have!

One possibility is that the PCM thinks it is protecting the engine from serious damage.

I'd at least do a code reset (OBD Mode 04).

 

Nope, no codes, no mil on. No network codes either, which is kind of strange.

 

when your cranking over..what are the PATS lights doing?
top center dash... if flashing fast you have a security issue which is causing the no start.. if not or staying on then security is ok..
ive been seeing alot of PCM's and ecm's faillinig..lately

 

I was thinking that yesterday and verified the PATS light. It comes on when the key is inserted, then shuts off. It does not blink during cranking.

I got an o'scope today so I'm going to probe the computer and the CKP and if that turns up anything. If there's no problem, I'm going with a new pcm.

I'm curious as to how you jaguar techs diagnose a bad pcm? Is it just exhausting all other options? It's kind of an expensive "guess" to be doing a shotgun repair!