Fiesta electrical fault

[Mark48]

I have a Fiesta 95M that won't start.

The symptoms are it turns over but no spark, no injectors and no fuel pump. This normally means the crank sensor is gone but when I disconnect it and meter it on crank over I get 1.4v AC so I think it is OK.

The wires that should go on to pins 5 & 6 on the ignition module read short curcuit so I assume the ignition module is faulty but it isn't on the bulk head like normal models so where is it? Do some models have the ignition module built into the EEC? It says in the haynes Manual that it doesn't cover revised 95 versions of the fiesta so I assume that is what I have. HELP...

Oh and I am not sure how the imobiliser works on this model (it has a chipped key) but when you turn the key the red LED on the clock module lights for 3 secs and goes out and does the same when you turn the key off. This might mean something and might mean nothing. Also I have tried the red and black key with no difference.

Thanks for taking the time to read this.

[nighthawk]

Some EEC IV equipped cars do have Internal EDIS, although without more info on your car it's hard to tell you for certain. Sometimes things aren't that obvious under the bonnet.

1.4/1.5 V ac is about right for a functional crank sensor and good air gap setup.

On the 1.3 engine, with internal edis, pin 5 on the module wasn't used and pin 6 is a PATS connection. Pin 21 and 22 were the CKP iirc

What engine is this?
Does the fuel pump prime up when you turn the key on to position II?

The PATS system is fine there, it's doing it's self test for the 3 seconds after the key is on,

Have you checked the basics?

Are ALL the fuses OK?
Has the inertia switch activated?
Is the power hold relay powering up EEC IV?

hope some of that helps, if you post back with further details (engine codes and type), i'm sure someone can help

[Mark48]

Thanks.

The engine is the 1.4 CFI, the fuel pump doesn't fire up (disconnected the fuel filter and not even a dribble), F19 is OK and with my finger on top of the fuel pump relay I can't feel a click, I can see the interia switch on the haynes diagram but where is it?

I will dig the EEC unit out from the the passenger footwell tomorrow and take a look to see if there is power to it but F1 is intact. On the haynes manual Pin 1 is the power to the EEC but if I have an EEC and Ignition unit combined is Pin 1 still the power?

The only number I can see on the EEC without removing it is 94FB-DC and where can I find the engine number?

Many thanks for your help on this one.

[Mark48]

Update.

The 2 wires from the crank sensor definately disappear down into the bulkhead in the direction of the EEC module so unless there is an ignition model down there with the EEC on some models I am 99% certain I have a combined one.

[Mark48]

Another Update

This morning I took the wiring cover of the EEC and it is a 12FB-12A650-DC and the crank sensor goes straight in on pins 55 and 56. There is also 12v on Pin 1 as expected.

Now there are 2 wires tapped on to the crank sensor pair (1 black and 1 green) that disappear back into the wiring loom to heaven only knows where but disconnecting one of these removes the short curcuit.

The car still won't start but there is clearly a short curcuit on whatever is connected to the green and black wires, any ideas where they go? Oh and they are part of the main wiring loom so I would presume they are part of the fords wiring.

Thanks for reading all this stuff...........

[nighthawk]

Hi m8

The engine code is stamped on the silver chassis plate, thats on the front panel of the engine bay.

From what your describe you have indeed got a 1.4 pte engine with EEC IV internal EDIS.

Pins 55 and 56 are the crank sensor cables for this engine's control unit, and the wires you speak of branching off the wiring go to the PATS module. (PATS is passive anti theft) that should be found around the area of the passenger side front kick panel. also the inetria switch is behind one of the panels....there is a finger access hole for you to try it.

F1 is a 3amp fuse, this is the keep alive memory
fuses F19 and F20 should also be checked.

tests

Pin 1 & earth with ignition OFF.......look for battery voltage

Pin 37 & earth with ignition ON........look for battery voltage

Pin 57 & earth with ignition ON........look for battery voltage


checks on earths

pins 16,20,40,42 and 60 should also be checked for a good path to earth.


Any problems with V+ to the module might well be because the power relay has failed. More info would be great after you've made some checks.

[nighthawk]

I forgot to mention how important the vehicle details are, you say it's a CFI (single point injection) but that should have an external ignition module from memory and the CKP wiring doesn't go to the EEC, the EFI version has the internal ignition and does have the cables where you say.

look for a box in the top left of the silver plate marked
Engine/motuer with 2 or 3 characters in it, F4, or F6 etc.

HTH

Nighthawk

[Mark48]

Hi , I will do all those checks in the morning but the engine # on the plate is F4, what does this make it?

Thanks again.

[nighthawk]

The F4 series of engine codes are multipoint injection, where by each cylinder has it's own injector.

There are some big visual clues to distinguish a CFI from a MPI, the air cleaner of the central fuel injection equipped car is a large almost pancake shaped item on top of the engine, the Multi point system uses an oblong shaped air box at the side of the engine.

The Engine's electronic control units wiring is also very different between the 2, so it's important to get the details right from the off

[Mark48]

Yeah the air box is on the side not the top so it is indeed a multi piont engine. Cheers.

[Mark48]

I just spoke to the girls who owns this car (my sister) and she says it started not starting and cutting dead while driving down the road about 8 weeks ago and then it when OK until a few days ago when it stopped completely.

The point being it was intermittent before it died completely, this may point to something or it may be useless information but I am throwing it in just in case.

Cheers again

[nighthawk]

All information is good, intermittant running and starting concerns can be a pig to rectify, your case is helped by it's progression to a non start now.

Fix the non start and you'll cure the random chopping.

[Mark48]

UPDATE

F1, 19 & 20 all OK

Pins 16, 40, 42 & 60 all good earths (less than 0.5 ohms) and Pin 20 read 2.1 ohms but that should be good enough.

The news flash is Pins 37 & 57 have no switched 12v. This points to the ignition switch/power relay. In the haynes manual it is position V but that is the heat rear screen on mine so I will trace the wiring out and let you know.

Thanks again for the help.

[Mark48]

More info.

Pin 37 & 57 don't have switched 12v and meter 1 Ohm to earth so never will have in that state.

All the fuses are intact and a shorted power line would blow a fuse so perhaps the pinout on this eec unit is slightly different.

Stranger and stranger........

>> Edited by Mark48 on Wednesday 28th September 16:40

[nighthawk]

pins 37 and 57 both get their 12v feed from the power hold relay.

[Mark48]

I have just checked and they are definately short to earth so we have a serious power problem to this EEC unit. Relay V is usually the power relay but on this model it is the heated rear screen so any idea which one is the power relay on this model? I have checked behind the fuses but it is an awful jumble.

Cheers
Mark

[nighthawk]

I'm sorry m8, but your on your own with the power hold relay location, your variant of fiesta has lond since dissapeared from the TIS disc

It was designated as K46 to the trade, the V bit is just to show it in the hand book.

Your looking for a 4 pin relay, i seem to remember it being purple or yellow, but then again it's been almost 1/2 a decade since i've had my head under the dash of that model.

[Mark48]

I think this has something to do with the PATS unit because the PATS unit is killing the crank sensor and I have a hunch it is cuting the ECU as well. Any idea where I would find the PATS module?

Cheers
Mark

[nighthawk]

I don't think that the PATS is at fault here tbh, because you say that the little red led in the clock is staying on for approx 3 seconds and then going off when the ignition turned on. That shows the PATS as passing it's in built self test.

The PATS module could be in 1 of 2 possible locations, either down behind the left hand kick panel or behind the glove box. your looking for a BLACK box approx 4"x 3" with a single multi plug on one of the ends.

[Mark48]

Hmmm you are probably right about the PATS but I am confused. I have someone sending me a wiring diagram for this version so I dare say it will make more sense when I see the whole picture.

Thanks again for your efforts it is really appreciated.