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Topic: Scorpio wont turn over - intermittant issue - Help (Read 1213 times) |
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carltailfin
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Scorpio wont turn over - intermittant issue - Help
« on: Jul 6th, 2025, 10:08am » |
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Hi all, after a mammoth 6- month rewire project - all previous issues have been fixed - but I now have 1 new issue. The car does not always turn over on the key.- - this never used to happen before...... When I first connected up the battery on Thursday the car started immediately. It started every times on demand after that too - until the evening when it refused to start. On Friday after re-connecting the battery it started immediately again - and on demand every time after that - I even took it for a drive and all was well. When I got back I switched the engine off and tried to restart it immediately- and nothing - wouldn't turn over again despite repeated attempts. Yesterday it refused to turn over in the morning at first but after trying again later it started immediately- and on demand repeatedly.........until yesterday evening when it refused to turn over again!. This morning it still refuses to turn over! Throughout the whole time I have been keeping the battery on charge and it is holding steady at 12.8 volts - 14 when the engine is running. I have moved and joggled the gear selector but it still refuses to turn over in either P or N. Incidentally the warning chime does work when the drivers door is open when the selector is out of park so I am assummig the inhibitor switch is OK as the chime goes off when the selector is placed back in neutral. I can clearly hear the fuel pump power up on the key every time. Also I note that even when the starter does not turn, the radio goes off the instant the key is turned to the start position in the way that is normal when much power momentarily has to go the starter- so would I be right in thinking this means the starter is getting the juice. Is it likely to be a starter motor issue rather than inhibitor switches, relays, electronics or PATS? Any suggestions on how to troubleshoot the issue would be greatly appreciated - its now giving me a headache!! Was wondering if it is possible to take the case off the starter inhibitor relay to verify if it activates when the key is turned - just to eliminate this from the possibilities - any suggestions folks? Thanks! Carl
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brds
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Re: Scorpio wont turn over - intermittant issue -
« Reply #1 on: Jul 6th, 2025, 12:57pm » |
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Can you hear the starter solenoid click when you turn the key?
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carltailfin
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Re: Scorpio wont turn over - intermittant issue -
« Reply #2 on: Jul 6th, 2025, 3:46pm » |
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Hi there - no the solenoid is silent. I have been tinkering all day and got a little further on. Here is the latest: With the inhibitor switch relay cover removed, the engine starts fine if I manually activate the relay with my fingers. I have tested the feed to the relay by placing a wire in each of the relevant connector holes and found it only gives 4v with the selector in park - not enough to activate the relay, and it gives only 3v in neutral. All other selector positions read 0v as you would expect. I was expecting to see 12v or nothing in the park position - but 4v? That has got me stumped! Every other electrical/electronisc system on the car works perfectly.......... Any suggestions?
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brds
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Re: Scorpio wont turn over - intermittant issue -
« Reply #3 on: Jul 6th, 2025, 5:21pm » |
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Looking at Dwg 26-01-001 (Starting System), with the key in position 2 or 3, you should have 12V at the Start Inhibit Relay coil contact 86. The other side of the coil (contact 85) should be receiving earth via the Transmission Range Sensor in position Park or Neutral. If all that is OK, I would suspect the relay is faulty.
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carltailfin
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Re: Scorpio wont turn over - intermittant issue -
« Reply #4 on: Jul 6th, 2025, 5:37pm » |
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Hi brds - thanks for looking in to this with me. I have tested the relay on the bench and it works fine with 12v going in to it. The problem I seem to have is that the car is feeding only 4-5v to the fusebox contacts 85 and 86. I would suspect the battery but it is constantly on charge a the moment and turns the engine over no problem if I manually operate the inhibitor relay. Any ideas why there is only 4v at the feed point to the relay? Cheers! Carl
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brds
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Re: Scorpio wont turn over - intermittant issue -
« Reply #5 on: Jul 6th, 2025, 6:34pm » |
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You should definitely not be getting 4-5V at both contacts 86 & 85.
Unplug the relay. You should then get 12V at contact 86 from the ignition switch and something approaching earth at contact 85 from the transmission range sensor.
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carltailfin
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Re: Scorpio wont turn over - intermittant issue -
« Reply #6 on: Jul 7th, 2025, 12:05pm » |
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Hi brds - all sorted! Yipee! Your info re: the contacts 85 and 86 and that the inhibitor switch gives a gateway to ground gave me some ideas on further testing I could do. Bits of wire, a multimeter and a few hours later the culprit was found! It was a lazy connecter inside the hole of the fuse box for pin 85. I put a very slight bend on the terminal pin of No. 85 of the relay and the connection was reliable again - 12v, working relay, car starts - all seems good! Thank you for all your help and time brds - you are a life saver!!!!!! Scorpio thanks you too! Have a great week! Cheers! Carl
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carltailfin
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Re: Scorpio wont turn over - intermittant issue -
« Reply #7 on: Jul 8th, 2025, 8:13am » |
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Spoke to soon - must have been a fluke when testing it with wire and multimeter that the real fault decided not to happen at that very moment......seems unlikely but there you go! Car wouldnt start in Asda car park - even though it started fine repeatedly when tested at home..........Now suspecting the inhibiter switch - does anyone know where this is? Cheers! Carl
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brds
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Re: Scorpio wont turn over - intermittant issue -
« Reply #8 on: Jul 8th, 2025, 8:28am » |
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The relay is the inhibitor switch. When it operates, contact 30 feeds 12V from the ignition switch to the starter motor solenoid. Ref wiring diagram 26-01-001 etc.
Suggest you check that you are getting 12V at the solenoid. If not, but OK when you manually operate the relay, are you getting 12V at the relay coil contact 86 from the ignition switch and, earth (may look like a low voltage) at contact 85 from the Tranmission Range Sensor.
If all that is OK then you probably have a dodgy relay so try a replacement.
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szinyei
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Re: Scorpio wont turn over - intermittant issue -
« Reply #9 on: Sep 7th, 2025, 6:45am » |
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Hi,
Look at the very recent post in problems.
It is an EDIS rewiring issue. I had the same. Have you already went through all those steps I described there? If values are for the ECU not correct from the EDIs, it will not let the car start. Silence.
Regards,
Csaba
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