Hi guys I am new to this form. Hope you all are doing well. So I have a technical question. I currently have no communication from my obd2 port. It is a Jaguar XF 2.7d Premium Lux. What I have done so far is ive checked the resistance between pin 6 and 14 and its 60 ohm I've also checked both grounds to the port as well as the live and all seems fine. The voltage on the high side is 2.7v and low side 2.3v so that seems fine. I am suspecting a module on the high side bringing the canbus down. Reason for me saying High is that ECU, TCM and Transmission modules not available with some others. Now my question as a noob how would I be able to determine what is causing my issue without the ability to actually scan the car.

 

Are you sure your OBD2 device is working correctly? Have you tried it on another vehicle?

 

Well I have tried a few 2 cheap OBD2 scanners with Torque (lite) app on my phone. Then I tried a Hawkeye the mechanic I borrowed it from says that I should use the Discovery 3/Diesel one as the engines are the same and I should be able to read the ECU using it as he has used it before on Jags and was able to read ECU and transmission modules as they are the same.

 

And in all of these cases you were unable to communicate with the car ECU?

 

Yes ecu, transmission (TCM, RDCM), Transfercase and Cruise Control modules are not available

 

You've got 12V between pin 4 (chassis GND) and pin 16 (battery)? I think you should also have 12V between pin 5 (signal GND) and pin 16.

 

Thanks a million Ive had to pay a guy to come out. It ended up being the scanner. The can bus systems are not the same and wont scan. Now to get it to start. Ive got P0336 crankspeed sensor error and no HPFP pressure at the injectors. Wondering if these might be related?

 

Which engine does it have? Do you have any DTCs other than for the crankspeed sensor?

 

Absolutely no other dtc's besides that and a amber engine light on the dash. Other than a amber engine light.

 

what engine is in the car?

 

Sorry it's a 2.7tdv6 im replacing the sensor tomorrow. Hopefully it controls fuel feed aswell. Will keep you updated. Apparently its a transmission off job but have read its possible although difficult.

 

Some details below about the sensors.

Hard to know if the two error are related, I'm assuming if the ECU is reporting low fuel pressure then the sensor must be working. I'd guess that without a functioning crank position sensor the ECU can't send the correct instructions to the high pressure fuel pump.

Reading the manual it appears you access the crank position sensor by moving the steering gear to one side, fairly straight forward other than the 100Nm of torque used to bolt the steering gear together, someone is going to get strong arms.

 

Turns out water damage on the ECU

 

Good morning guys. Okay so just an update. I got the ecu out had the resistor repaired. Put it back in and pop when I turned on the ignition. So I am now trying to figure out:

1. Is the ecu shorting out?
2. Is there a dead short somewhere in the car?

The resistor that fries is the injector control module as that is the only fault the ecu reads out. Any ideas or advice would be appreciated. This has my head confused now. A fresh mind could help me find the issue. Please

 

Do you have a short on that circuit?
It appears you do so track down what's shorted out in that circuit before reattaching the ECM.

Do you have the pin out diagrams to check the ECM plug?

If nothing is shorted out then look to the ECM. But who fixed the ECM?
Did they do it right?
Did they check for additional damage to the ECM?
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Thanks for the reply. Much appreciated. Would the short be associated only with the injectors? As it is the injector driver that keeps failing. Some ecu guy repaired it. South Africa doesn't have that many guys who know ECU stuffs that much. He came suggested by a local mechanic. Ive spoken to him and he asked that I send the ecu back to him for testing.

Looks like he repaired the blown resistor and sent it back..

My biggest question is how can I locate the short? Can it be a component somewhere thats shorting? Since its the injector driver resistor blowing does that mean look only at the injector wires and injectors themself?

I dont have the wiring diagrams if anybody could assist me with a copy

 

Have you done any searches?
I find the XF electrical diagrams here;
XF Electrical Diagrams

Might be worth a download and look?
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Yes Thanks for the help ill have a look at it and try and test things out thanks again

 

This might be too big but it's for the early XF. Note the serial number range it covers.
Please let us know how you fixed it too!
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Ill definitely keep you posted thanks