Hello

My 2005 3.0 auto (LHD)hit a huge pothole on passenger side front tire and died immediately--no start with transmission fault. My scanner has no connection with ecu. I have replaced:
TCM
ABS module
Shifter
donor vehicle ecu/Instrument panel/keyswitch

Scanner shows:
TCM code P1797
IP--B2141 and U1900
ABS U1900 and U2202
ECU--no communication

looking for any tips--thanks!

David
2018 XE
2005 2.5
2005 3.0 (dead)
2005 Vanquish S
1991 Lotus Esprit

 

Wahooesprit, going to ask a silly question, but because you hit the pothole on the right side of the car, have your tried resetting the inertia switch in the passenger footwell area. If you pull the plastic cover off at ankle level (at the door hinge), you will see a push button there, depress it and see what you have then.

 

Thermo wrote it first - I would have written the same reply....

 

Yes I did reset the inertia switch previous to the other new bits installed

 

It strikes me odd that you cannot connect your OBDII scanner to the Jag. Was that possible before the pothole?

Was the pothole that huge and the surroundings of that pothole that awkward that it is possible that some cables were torn off from underneath the Jag?
I don't know by heart where each and every cable is, and if that would be possible...
On the other hand, maybe the mechanical shock vibration was that big that somewhere a big cable snapped off, because it had pre-damage? Are all the earth cables properly connected - without corrosion between the contact surfaces (maybe the pothole-shock moved a cable a bit, and now the last bit of contact surface behind one of those cables was lost and there are now only corroded surfaces meeting each other - that one is far fetched, but not impossible, I guess...

I think, you get a "transmission fault" message (and the car would not start), when the ground cable under the battery box being screwed onto the transmission is not connected or does not have contact.

PS: Also follow that earth cable all the way to the other end, wherever it is coming from - maybe that one was torn off somehow on the other end or in the middle...

 

Peter

Thanks for the reply. Yes the scanner worked before--I actually keep it in the car to clear the occasional P0430 code that pops up (to lazy to swap the cat out). The pothole was large enough to drop the whole tire in but didn't scrape anything. I had to jack the car up to access the cable to the transmission to put in neutral so I could move it after tow truck dropped it off. I have since swapped the engine fuse box and followed the grounds and cleaned each one and retorqued them. Almost to the point of swapping the 2.5 ecu/cluster etc but that car is a 5 speed so probably won't work.

Regards

David

 

Update...

Thermo/Peter

You guys made me think about the inertia switch. So I took the switch from the 2.5 and swapped to the 3.0 but no change--still no communication with ecu. Funny thing is the 2.5 would not start with the 3.0 switch in, but started when I put the 2.5 switch back in....still hunting

Thanks

David

 

Wahoo, did some looking at the diagrams. I would first start with replacing relay R7 in the engine bay fuse box. R7 pretty much puts power on everything with the power train (engine, tranny, ABS, etc). So, this single relay can cause a lot of heartaches. After that, I would access the ECU (passenger side of your car, just behind the front wheel in the cowl area. I would look over the wiring first just to see if you can spot any obvious problems. From there, you need to locate pins 22, 23, and 24. Pin 22 should have power all the time and 23/24 having power when the ignition switch is in the RUN position.

Lets start with these checks and see where they go from there. The other potential we have here is the shock shook the snot out of the ECU and it busted the ECU. But, lets see what else we have before we jump down that road.