Crank Sensor ordered- not really convinced it’s a solution, but while I am throwing parts at the car, why not?

 

I know it can cause starting problems and intermittent stalling but, idk if it affects complete electrical failure at start up. I suppose if it can cause stalling it might act that way at ignition start up. Most of what I read said the car cranked but, wouldn't fire or it died while driving.

 

Found an old, old (11 years ago) Thermo post on diagnosing no start at key ignition. Worth a look =

first, I want you to remove the R10 relay (starter relay). Locate Pin 1 on the relay. Now, relate that to pin 1 inside the fuse box. Connect a multimeter between Pin 1 and chassis ground (set multimeter to read 20 VDC). Do you get 12 VDC when you rotate the ignition key to the "START" (III) position? If no, then you have a problem with your ignition switch or the wiring between the ignition switch and the relay. Let me know and I will give you further checks to make if you can't figure it out. If you do get 12 VDC for this check, next move the lead from Pin 1 and put it into Pin 3. Do you have 12 VDC here (doesn't matter the position of the ignition switch for this check)? If no, replace fuse XX and if you still don't have 12 VDC, then you have a wiring problem ​​​​​​.

Finally, using a set of alligator clips (or the aide of a friend), connect up the multimeter to the large post of the starter and chassis ground. Now, using a piece of 14 gauge solid wire, install the piece of wire between Pins 3 and 5 inside the fuse box. Does the multimeter drop but stay above 11.0 VDC? If the voltage stays at 12.6 VDC (above 12.3 VDC), then move the multimeter lead over to the small post and see if you have 12 VDC there? If not, then you have a wiring problem between the relay and the starter. If you got between 11.0 and 12.6 VDC with the multimeter lead on the big post of the starter, then your starter is attempting to start the car, but it can't develop enough torque, new starter is required. Finally, if the voltage dropped below 11.0 VDC, you have a bad battery cable, corroded terminal on the starter, or a bad battery. Repeat the check but with the multimeter across the battery (vice across the starter). Does the voltage stay above 11.0 VDC? If yes, then bad cable/connection. If no, bad battery.

 

FYI, if you are suspicious of the throttle body, I cannot think why it would create a 'no crank' scenario.
A 'No start' outcome yes, but to tell the ECM to inhibit cranking, I am struggling to come up with a logical theory for that scenario.
You unplugged the TPS and still had cranking, but generated error messages.....an expected outcome.

If it is the TPS, the only scenario I can think is that one half of the TPS was not giving a reading tot he ECM (it has dual operation variable resistors - each tracking position but one increasing while other decreasing in resistance - same as pedal sender unit).
I am wondering if only one resistor track was giving a reading, the ECM might decide with that failure to inhibit crank, but in saying that when the total TPS was missing (plug disengaged) I would expect a similar result out of the ECM.

Seems that there are a few 2nd hand Throttle bodies around e.g. eBay item number: 274774716175

Physically the TPS units appear to be riveted onto the throttle body and I can't for the life of me find just the TPS sensor pack.
FoMoCo # 4X43-9F991-AA.
I can see new TB units on Alibaba out of China, but whether it is possible and/or practical to drill the rivets and transfer just the sensor pack over to yours if your throttle body is good and you don't want to run a risk on the whole assembly quality.
That sensor pack just doesn't seem to adorn many other models. Some S-type maybe, but little to no other Ford production......appears very slim and nothing close in Volvo range either.

Keep the info coming as to what you are seeing and eliminating and we will keep wracking our brains for you.

 

if only the car would throw us a bone. Throw us a code actually. This is so unfortunate, I had money allotted to installing the new shocks/struts and control arms and whole bunch of new suspension parts I have ready. Now I may have to use that to buy the 700 tps that may or may not work

 

Hey, persistence might have won out!
Finally found a similar looking TPS unit which is used on Mazda throttle bodies in the production models of the Demio range from 2002 to 2007.
Could be worth investigating part number ZJ2013640A
Might be physically compatible TPS at a better price, just hope resistances are similar (no reason not to be) Ford/Mazda/Jag/Volvo were all dipping into similar parts pools.

Here are some pictures.

Mazda Demio # ZJ2013640A

Mazda Demio # ZJ2013640A

Hope this is useful info.

 

THNKS!

I am also finding that several toyota TPS look identical! I am finding several Toyota Tacoma TPS that look the same too….I will keep on searching !

thanks again !

 

Whats the old saying........If at first you don't succeed - cheat and change the rules!

If you can find a donor body with a similar TPS, you might be able to just sit the donor alongside so you can divert your plug into that TPS instead.
Hopefully with everything at idle if might give you a quick answer without having to commit starting to deconstruct yours.
It just won't give any change feedback to ECM if you operate the accelerator pedal.
Not sure how high idle might react for a cold engine....just be ready to turn ignition off if engine revs race.

 

What you can't see in this exercise is the TPS drive spline size, shape and its rest position.
That can be the source of variants in part numbers, yet alone resistance, plug type, plug position, casing shape and mounting holes.
Went through all of this on my 2.1 recently as no TPS spare part from Jag either.
Did find an equivalent though and shared that success to forum just recently.

 

Hello gents

Still no CEL

BUT, the car shut down on its own as I was idling in the supermarket parking lot….before I restarted the car, I hooked up the scanner and codes did come up:

P0629- Fuel pump A
P1637>
P1643> These are comms codes and appear in 3s
P1699> When the car shuts down

**CEL and codes went away once the car actually started***

My philosophy is always to follow the first code. I am discounting the comms codes (right now) because the car only shuts down at idle or at low speed when coming to a stop. It never shuts down at higher speeds. If the car looses comms it could be at any speed IMO.

Fuel pump is a couple of years old and when car doesn’t start it’s a NO CRANK, NO START so I am putting that aside for now too

I am assuming that something is not letting the car crank/start and sending a signal, and also loosing the signal at idle and lower speed randomly

Gotta be the CPS or the TPS. ……..I HOPE

CPS is on its way. Gut feeling tells me is the 600 dollar TPS.

I think that in order to really eliminate doubt only the real Jaguar part will do. God Almighty have mercy on my soul and wallet .

My friends have Hyundais and Honda’s that are in the 200k range that they barely maintain and never break down……oh yeah, but they look like blenders…

 

You might try contacting AIP Electronics in California to see if they have a throttle body with the built in sensor. Their price on most things is pretty good. They may even be able to rebuild or test yours.

https://www.aipelectronics.com/

yup, they do

 

I had cranking but not starting intermittently. Had the "Cruise Not Available" warning a few times when it would not start. Tended to start every time when it was cold. Had the engine just cut out while driving once. It was all the fuel pump. I agree your situation is completely different as you have no cranking, but maybe the dying while driving and other behavior is a bad fuel pump, secondary to your no-crank problem? The symptoms sound like mine, and you did get a fuel pump code. I have a $15 Bluetooth code reader and the free Torque Lite app and managed to data-log fuel pressure after I put in the new pump. The ECU reports about 53 to 56 PSI. If you have a code reader you might log the fuel pressure, the throttle position, etc to see if you find clues. I set mine up to log what I want then start logging before I start driving. That way I can pay attention to the road and not be staring at some gauges on the phone. Below is my fuel pressure on a 30 minute trip with one brief moment of wide open throttle at about 7 minutes when I tried to avoid getting hit by someone hurtling at me.

 

thanks for your reply. I appreciate your response.

I don’t think our symptoms are very similar, I haven’t had a “crank no start” situation at all, (yet). The car either will “no crank/no start” - specially when left overnight, but also randomly thru the day, or simply die at low speed air at idle.

I replaced my fuel pump a couple of years ago, so there’s that too….

I will keep the fuel pump as my third option behind the CPS and TPS at this point.

CPS came in yesterday, just need to figure out how to replace it

 

 

Thanks. Got it done today.

The old CPS was cracked:




I was cautiously optimistic.

car started fine 3 times. No crank/no start of 4th attempt. (CAR ALWAYS EVENTUALLY STARTS NORMALLY AFTER SEVERAL ATTEMPTS OF SILENCE/ NO CRANK /NO START). Car has not died at idle or while slowing down yet.

So no resolution. Maybe I had two problems?


I think it’s the TPS. If it dies again at idle or coming to a stop it’s gotta be the TPS. On the flip side, I have never heard of a TPS causing a no crank no start

ahhhhh.

 

No dying at idle or slowing down , and only one instance of no start today.

Spend hours upon hours with the car running and me pulling and poking cables, tapping fuse-boxes, tapping the TPS, connectors, wires in the engine, in the steering column, hitting the top of the dashboard lightly , giggling the wiring that goes to the pats ring, underneath the steering column, on the passengers side, on the trunk , back on the engine jiggling the battery cables. I am exhausted.

And I can’t duplicate the problem. Might just get a new key cylinder and that new TPS and pursue that. Those two are high on my list right now.


I would just keep on driving until the problem is so bad that the car totally dies and the problem becomes obvious…..problem is that this is my daily driver, and I transport my 84 year old grandmother in this car to her appointments, we go to Mass in this car etc. The E type and the XJS are too low for her. Hell, the X type is too low for her…so there is a bit of urgency there.

I thought that cracked CPS I changed in my previous post was the answer.

Hopefully tomorrow is a better day.

 

I'm laying odds it's ignition something. TPS can make car not start but it turns over. It's usually telling the ECM you have the gas pedal all the way to the floor (flooded mode) & no gas is introduced.

 

Ordered new ignition barrel today thru the dealer 230 bucks. Not terrible and I can now rule that out ……

I though maybe the whole dying at low speed thing was cured by the new crank sensor.

no such luck. On the way back from the dealer as I was going a bit slow, car momentarily blacked out and came back on. Windshield wipers go of on their own, ABS light came on, all engine power lost for 2 seconds and then all back to normal .

My XJS blacked out like this when the TPS was shot.

I need to get this ugly episode done and over with, I have new control arms, all new shocks etc that I want installed and I really can’t until I know this is fixed.

 

Hey Mark,

I truly can't see it being the TPS on the throttle body creating a no crank situation, simply the ECU doesn't care about the TPS position until the car is actually started.
Unless you are having unusual throttle behaviour, flat spots, erratic idle, then I myself would hold off spending on this expensive item until you exhaust the more likely culprits.
Gone back over the schematics again and again as I feel we must be missing something.

The ignition switch has two critical outputs involved in the starting of the car.

• The first is the less obvious one as the barrel assembly/switch has a key insertion switch to acknowledge the key is physically present in the barrel - that sends 12v from plug IP18 pin 5 to the General Electronics module plug IP6 pin 8. If that is missing then GEM will not send "OK to start" via CAN Bus data to the ECM.
• The second is when you roll key to position 3 (start) - 12v is sent via plug IP18 pin 7 to the Power Distribution fuse box plug JB205 pin 7 (to the R12 start relay coil positive side) which then also loops straight out of the PDFB via JB205 pin 8 to the ECM plug EN16 pin 006 pin (the engine request crank input).

So if you have the 12v 'key in' voltage reliably to the appropriate input of the GEM, and you have 12v start position going in the power distribution fuse box, then you need to check that the ECM is trying to pull the start coil low via plug JB206 pin 8 of the power distribution fuse box.
If pin 8 not going low on start request, then the ECM is being told not to allow start motor to engage.
That then means the ECM is either:-
Receiving a bad input from the park/neutral switches - the ECM should be getting 12v to EN16-031 if gear shift in appropriate position (chime would be sounding if not I would have thought).
Or the passive anti-theft transceiver is not being satisfied or communication properly to the instrument cluster that then sends CAN Bus acknowledgement to ECM 'OK to start".

If the ECM is pulling the start relay coil low, then you need to check you have 12v supply to contacts of relay R12 and the contacts are closing properly to send 12v to the starter solenoid to engage the starter motor.

I have highlighted the relevant pathways on the schematic below for you to hopefully help.
My gut feeling is you have a mechanical issue with barrel or ignition switch stability that is occasionally losing one of the two 12v outputs needed by the ECM.
You could have a freaky intermittent wire/connector in any of the above signal transfers (so when you are checking signal outputs, make sure they are reaching the destination).
Lastly is the RFID module could itself be intermittent, but that is harder to check apart from opening and looking for any dry solder joints inside initially before outright replacement. (again this would be one of the last options).

 

thanks so much- I have been looking at these schematics myself

A new barrel has been ordered today and the ignition switch is new. But I don’t think this explain the dying at slow speed and blacking out completely. I guess it could be speed sensors too. This is quite exhausting