cliftyhanger
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| posted on 1/3/23 at 03:54 PM |
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Mondeo non starter
Back with another Q about the BILs Mondeo. 2008 TDCI
It just didn't start a few days ago. BIL decided it MUST be the battery so went and bought a new one. No different.
I phoned him today (on a different matter) and he told me, so I popped round with a meter and few basic tools.
Indeed the battery is fine, everything works, just not a peep from the starter.
So I pulled the starter "trigger" relay, and jumped that. Starter worked fine. Swapped the relay for another in the fusebox, no different.
I then tested the 2 "coil" connections to the relay. Neither seems to be earthed, and neither gets 12V when the key is turned. Which sounds
odd, but I have no idea how to test further.
Does anybody have experience or knowledge?
Please bear in mind I am invested in this car. I borrow it when I need to tow a car trailer, and I am hoping to collect a couple of cars in a few
weeks time. If he changes it, he is talking of an ecoboost focus
Ta.
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Prof_Cook
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| posted on 1/3/23 at 05:56 PM |
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You say that when you "jumped" the trigger relay the starter worked fine.... did the engine run?
Bit hard to diagnose from the description, but could be immobiliser issue? Have you tried BIL's spare key?
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cliftyhanger
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| posted on 1/3/23 at 06:07 PM |
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No, I made him stay inside making tea, so I used a bit of wire to joint the perm 12v to the starter motor connection (the 2 large terminals on the
relay) which got the starter turning. Key was in teh ignition on position, I think. But I am questioning myself now. I really wanted to see if the
starter motor was the issue.
A bit of digging suggests the ecu may control the relay coil earth, but I am not certain as reliable info is difficult to come by.
As to immobiliser, no idea what level the immobiliser works at. Certainly has lights, wipers etc. I will suggest another key. And I will check to see
if I can get it to run by jumping the relay. As the car is worth 50p, I am tempted to suggest I install a starter button if it turns out it will run.
Ta
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Sanzomat
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| posted on 1/3/23 at 07:56 PM |
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I think the immobiliser suggestion is a good one. Starter is a common circuit to protect with an immobiliser and they typically interrupt the earth.
If the immobiliser isn't allowing the starter relay coil to earth then there will be at least one other circuit it is protecting (often ignition
or fuel pump) and likely a handshake with the ECU itself. First step is change the keyfob battery and might to need the key re-programmed. If there is
a spare key try that first.
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Mr Whippy
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| posted on 2/3/23 at 07:57 AM |
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Have you tried using any other keys or changing their battery? just to rule out the key not being picked up...
I'd also have a good look through the fuses for any that have blown and maybe swap out the relay for the starter. Also check the engine earth
strap is a good connection along with any of the other engine bay earths. Car ECU's seem to be very reliable and I always found issues were just
down to loose wires or poor connection which can lead to all sorts of weird problems.
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obfripper
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| posted on 2/3/23 at 11:38 AM |
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With the ignition on, is the mileage displayed on the odometer, or have you got dashes inplace of the figures?
If dashes are displayed, there is a communication fault between the engine ecu and the instruments, with the immobiliser being part of the
instruments.
Usual cause is dry solder joints between the instrument panel pcb and the connector socket. The instruments need full disassembly to reflow the
solder, and the zero position of the needles needs marking before removing them as it is often not at the gauge zero mark.
Sometimes giving the cluster area a firm bump can be enough to make contact and allow an engine start, obviously not a fix, but might allow you to see
things work correctly.
The engine start is blocked at ecu level when the immobliser is active, so even if you activate the starter and fuel pump, no start is possible.
If the mileage is displayed correctly, check the red led in the cluster, iirc it still flashes a fault code sequence if there is an immobiliser
problem, normal operation is on for 1/2sec and then goes out.
Dave
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cliftyhanger
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| posted on 2/3/23 at 02:13 PM |
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Update.
RAC chap got as far as I did, but stuffed a wire into one if the relay connections to activate the relay and that can start the car.
I paid a visit, hoping it would be the ignition switch. But no, 12v in the bottom wire appears when you turn the switch. Checked continuity in this
wire to the relay connection. Nothing, suggesting a break in the wire?
And a curveball. Headlights come on with the ignition, whatever position the headlight switch, and main beam not working. BIL noticed this when RAC
man was there.
Happy days. Is this coincidence or related? Give me an old Triumph anyway....
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gremlin1234
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| posted on 2/3/23 at 03:09 PM |
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one thing to check is if one side becomes live when you turn the key,
do you normally have to depress the clutch when starting the engine? if so could just be a simple switch on the pedal,
EDIT: sorry just noticed a post in which you answer the first question.
[Edited on 2/3/23 by gremlin1234]
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cliftyhanger
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| posted on 2/3/23 at 04:04 PM |
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I have "temporarily" run a surfaced wired from the relay (replacing the RAC mans 6 inch bit) and connected it to the ignition switch so teh
car starts with the key. So he can drive the thing.
Dipped beam still always on with the ignition, no main beam. No matter what you do with switches.
I am done for a while.
Oh, as I was leaving I noticed a screw in his tyre. "must have been one I dropped when changing the air filter" he says. Another one for me
I expect.
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bigrich
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| posted on 3/3/23 at 09:17 AM |
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I had something similar on a fiesta that turned out to be the main harness loom earth that had broken about 4 inches back from the ground point on the
gearbox. This stopped numerous circuits and the immobilizer from working. I too could bypass and get a it running by adding a wire into a relay to
bridge it.
.JPG)
A pint for the gent and a white wine/fruit based drink for the lady. Those are the rules
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