So I have been thinking and chime in if you have an opinion, The wires I have been measuring have had resistance readings all over the place. pin1 to 3 pin 2 to 3 ect on the Fuel Pressure Monitor.

If I get a low resistance reading on a circuit say 300 ohms and use that wire for a test in another circuit and resistance is higher say 5kohm the resistance potential on that wire is still 300 ohms or less....is that correct?

 

I have no idea what you just said. Have you:
1) disconnected BOTH ends of the pressure circuit at the same time and then measured each of the 3 wires from end to end. Each must be 0 ohms. If not, you have a partial open.
2) then measure across each unique pair at the p sensor end? Those should be infinite. If not, you've got a short.

Until you've reported on those two basic measurements, really don't know what you've got.

 

Thanks XJRS and Matt

XJRS,

I attempted to check the wiring as you described yesterday but pulled the wrong plug on the PCM to measure and was getting readings all over the map. This lead to the incorrect conclusion the wiring was bad in that circuit.

I am going to check the PCM to FPM circuit at a later date if I have time before it goes to the dealer in February.

Matt,

I checked the battery ground its fine and there are three grounding lugs on the firewall near the primary PCM. They look fine but I will break the nuts loose and spray with some deoxit and retighten tomorrow.

Battey was as 13.3v today but it was cold this morning and I did not charge after the stress tests yesterday. I put a 1.5 amp charger and I am going to let it run all night.


Thanks all

 

Back from Mexico! ...
Checked all the grounds and they look fine. The whole engine bay, wiring, and all points are immaculate on this car.
Problem did not go away which is a good thing. The car is going to the dealer in Nashville next Friday so we will see what they come up with.

 

Well Car was at the Aston Martin dealer all day today and apparently this problem has got them stumped. I feel better and worse all at the same time

 

This thread is old but I am determined to see it through the repair of the vehicle.

Music City Motors in Nashville called yesterday and the apparently are confident they found the problem. They replaced the potentiometer on the throttle pedal and the car is running. How they found the problem there is beyond me but I will report once I speak to them.They are going to go over the car monday and test drive but I am happy!
Eric with Music City has been doing a great job trying to run this down and baring any unforeseen gremlins I will have my car back next week!!

 

Glad you are getting your car back, but it does seem a little odd that the throttle potentiometer on the peddle was the problem, but then again considering how everything is so entertwined in modern cars, guess the interior light going bad soon will start causing the car to go into safe mode. LOL

 

It sure is odd to me as well randyb. I guess if one of the potentiometers goes bad I can see why I had the readings/symptoms I had. One would think the PCM would report a bad pot. I think once the car goes into limp mode the PCM limits the throttle on the good side and disables the throttle on the bad side so diagnosing a bad throttle pot could be problematic.

 

I spoke with the dealer today. He quoted 860.00 for the dual pot throttle pedal. I do not know what the labor will be but it looks like a couple of bolts and 2 plugs.

At last tally the dealer had 6 hours of diagnostic time for the pedal. They acknowledge the time is high and are going to "work with me".

I will see tomorrow I hope

 

I was wondering how a throttle pot would affect only one side, but then you said there were two. They truly set up that car as two separate "motors", even down to the throttle input. I've seen pedals go bad and start giving erratic readings, but never just die. I'd be curious what the failure mode was. Glad they found something.

David

 

Yep me too. Two of everything, although handy when trying to diagnose a problem, means twice as much stuff to go wrong too.

On a side note unfortunately they found a cracked window washer bottle from where the jack slipped off the lift point and cracked the plastic. I am sure Aston wants over 500.00 plus labor but I have not got the price yet.

The tally is starting to add up and I don't have a firm labor figure yet on the other repair.

Joy of ownership is slipping

 

That's not right. There are two for safety, not for separate left and right bank inputs. They must agree within a certain amount, otherwise you get limp modes and other safety related limits.

 

So do you think the Aston Martin dealer is giving me a lode of BS?

 

Anyone have the schematics for the Throttle petal.

 

Just got off the phone with the dealer and they quoted 1200.00 for the windshield washer bottle installed....Wow