Great diagram. Thanks for sending.

 

Hi everyone. Looks like I have trouble right here in River City. I have fault code P0706. The previous owner said she had a similar problem. She bought a replacement TCM (transmission control module). She said she never got around to putting it in, so it arrived in a box in the truck.

Well, I was certain that I could solve my problem by swapping the TCM. NO ... NO ... NO ... NO. Boy oh boy am I ever stupid.

Swapped TCM. Could not get the car to start. Wife unhappy saying, well you know what she said.

Put original TCM back in. Reconnected battery. Same result. Cranks but no fire. Yes, there is fuel at the relief valve. Yes, I checked the micro switches in the J-gate.

I am at wits end. Can't start it. More than 60 miles from nearest dealer. And I have no idea what to do next, except ear plugs so I don't have to listen to wife saying, well you know what she is saying.

Very respectfully, Bob G.

 

Ok- let's break this down.

1. you have a transmission error code- has nothing to do with starting.
2. Iran, and now doesn't and there were no noises, correct?
Here is what you need to do next:
1. check the fuel pressure- is there any?
2. check compression on ALL 8 cylinders- what are the readings?

Once you have the answers to 1 and 2 we can give you MUCH better guesses as to what your problem is. After watching this forum for years, I have come to find a no start is 99% of the time lack of fuel, borewash or broken timing chains. We need the info above to figure out which it is. (or isn't) The other 1% is an electrical issue that takes awhile to find and sort out.

 

Thanks Dave. I'll check fuel pressure at the valve next. All the "bad" things, while possible, and highly unlikely (but you know more about Jaguars than I do).

The car started and ran fine in my garage. After I swapped the TCM (which is not part of the starting issue), I never could get it started again.

I fully concur with you about the fuel -- pump, blocked filter, relays, ...

Is there any SAFE way to squirt some fuel into the throttle body just to see if the engine fires?

I feel like an idiot.

Best regards, Bob G.

 

Biob,
I would forget the 0706 for the time being - it should not prevent the car from starting.
So - you have done something along the way I suspect.

With ignition on, engine cranks OK - yes ?
With foot on brake, can you get out of "P" - do you hear solenoid click - yes ?
Check connections to throttle body - have you dislodged any of the connectors ?
You have fuel pressure ?
If you have disconnected TCM - double check none of the (many) pins have been bent of damaged. You HAVE put the original back - yes ?

Did you disconnect the battery before exchanging the modules ?

None of this is being critical - just trying to help :-)

 

Thank you DevonDavid. Starting get dark here in Florida which means the mosquitoes are about to go out for their nightly feast.

I do most checking in the early morning, so I will make sure I do all you suggest.

Best regards, Bob G.

 

Actually, a bad transmission rotary switch or a maladjusted transmission selector lever cable can result in a non-start and your code points in this direction. Please see your other post. (I would start by trying to start the car in neutral or jiggling the gear lever in Park or Neutral.)

 

Hold on. Did you start the engine cold, drive it into the garage while still cold (not warmed up) and then try to restart it after swapping out the trans computers? now I am leaning borewash.

 

We just drove home the last 4 miles and parked it in the garage. It had failed earlier on the way home, when the RPM went to zero. I guided it off the road and waited, maybe 5 minutes. It started right up and we continued the last 4 miles. I was sure that the P0706 code had something to do with it. The prior owner said she had the same experience. She bought a replacement TCM, and it was in a box in the trunk (boot). I was sure all I had to do was swap the TCM. Hadn't tried to start it first --- I just disconnected the battery and you know the rest. I sure feel dumb.

 

Did the previous owner tell you why she bought a TCM? I'm still rooting for my try starting it in neutral approach (but won't be disappointed if that's not it !)

 

Dear Motorcarman, michaelh, DevonDavid, fmertz, mhminnich, and all others following this post.

PROBLEM SOLVED. Repeat: PROBLEM SOLVED.

It wasn't until I read the last paragraph in:
JagRepair.com - Jaguar Repair Information Resource

That I recognized what was wrong.

It says "If all attempts have failed you may want to look into the exciter ring located at the ignition lock. This ring receives a signal from your key that enables the starting process. This part of the no start process in not a common occurrence but should not be overlooked."

So here is what happened, and why I feel so stupid.

I own two 97 XK8 convertibles. One is called Baby Blue, and the other Black Beauty.

When I first bought Baby Blue, it naturally came with ONE Tibbe key and no FOB. I did a lot of research, and was able to buy another, NO TRANSPONDER CHIP Tibbe key. It worked perfectly. That is because the '97 XK8 Convertible does not use a transponder chip key.

Now along comes Black Beauty. Also a '97 XK8 Convertible. Therefore it does not need a transponder chip key. So I bought another key.

While waiting for the new key to arrive, I swapped the TCM as described earlier, trying to solve the RPM goes to ZERO problem. When I was done, and reconnected the battery, the new key arrives (no chip) so I use it to start the car. Cranks but no fire.

I'm desperate. Wife not happy, and she tells me so every 15 minutes.

I've been trying everything all of you offer. Voltage, fuse, relay, fuel, J-gate, etc. No luck. Then this morning --- VOILA. I send wife to garage with OLD key. Car starts right up. She is honking the horn to get my attention. I told her it was her magic touch.

Boy oh boy am I stupid. I assumed, and you all know that that means. Just because my '97 XK8 Convertible (Baby Blue) doesn't need a transponder key, I assumed that the '97 XK8 Convertible (Black Beauty) did not need a transponder key. BAD ASSUMPTION. 40 VINs apart.

So, I can start the car. (HOORAY). Now I'm back to finding out why the RPM dropped to zero on the maiden drive. Maybe I'll swap the TCM again.

Thanks for listening to a dumb a__.

Best regards to all, Bob G.

 

Glad to hear it worked out- may want to start another thread RE the stall thing. I am going to point to the throttle body on this one though-

 

Delighted to hear you are back up and running again! By the sound of it, I must have married your wife's sister. 😉

I was buying a car for my daughter not too long ago and ran into that same sort of issue. The seller was using the new key he just had made. In this case the car would start and then die a few seconds later. I suggested that he try the other key, and guess what, it started right up. I'm sure you have the same look on your face right now that he had!

 

So ............ you get the car started AND flattered Mrs Grisar (I think she should be treated to at least one expensive dinner !!). Some of us never achieve both those objectives in the same day !!

 

Have you checked that the Recall/Service Action '303-S514am Operation Of Throttle' was performed??

You might need a replacement throttle assy anyway even if the ECM was updated.

bob

 

LOL. No point in beating yourself up, Bob. Amazing how many causes become blindingly obvious once you find the solution...

Key thing is (sorry), you got it sorted

Mike