Intermittent start

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Guzzisvt

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I have a 2010 sho with 185,000 miles on it. For the past month when I hit the start button, put on the brake occasionally nothing happens. The first few times it started on a second push of the start button, but then it left me stranded after repeated button pushes didn't work. Where a guy where I was at had a jump box and the car started right up. So I went and got a new battery but a couple days after that it did it again, but then started on the second or third attempt. I went to AutoZone and had them check the battery and alternator which passed with flying colors. The next time it did it and wouldn't start I left it in the on position pushed on the brake and I could run the shift lever back and forth and back into Park. The car then started. Other times when this was attempted the car didn't start so I didn't push on the break while hitting the button, and the warning came up to push on the brake to start engine, so I did in the car started. This last weekend on my way to Santa Fe New Mexico I stopped in Amarillo at the Texan restaurant to have a steak. When I came out the car wouldn't start and after many attempts to start it I finally gave up and called for a tow truck. Of course when the tow truck got there and I needed to move it out of its space by putting in a neutral the car started. I took it to a dealer in town where they attempted over the weekend to replicate this but could never get it done. While at the restaurant I had a mobile service guy come from the dealer and do a software check on all the I/O of the computer. He said all the sensors were working, i.e. park switch, brake switch, security switch. So my first thing is to look for the start relay. Anyone else have this problem and does anyone know where to start relay is, thanks!
 

Texas Marauder

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Try swapping the starter relay with the wiper relay. Try swapping the run/start relay with the reversing lamp relay.

Verify the numbers on the relays are the same, they should be.

Also, possibly an intermittent Transmission Range sensor.

1697515584582
 
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Guzzisvt

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Try swapping the starter relay with the wiper relay. Try swapping the run/start relay with the reversing lamp relay.

Verify the numbers on the relays are the same, they should be.

Also, possibly an intermittent Transmission Range sensor. Check the connector and switch for corrosion.

View attachment 88680
Thanks, this was just what I was looking for. I see the start relay. What is the start/stop relay for?
Where is the transmission range sensor located?
 

Texas Marauder

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Not sure exactly what the start/stop relay does.

Unfortunately, the range sensor is inside transmission where the shift linkage is. Older transmissions had the range sensor on top.

The proper way to diagnose is to use a scan tool to monitor the PID for the range sensor. In other words, the PID should match the actual position of the shifter.
 
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kryptto

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Might I add - possibly a bad fuel pump control module will allow the dash to light up but no start - even typing this, doesnt sound like the issue. Just something to keep in mind. I pro-actively replaced mine, there was a recall I believe on the 2013-2010 for defective part - however 14-15 might still suffer, they ---- fudge it - found the TSB see attached.
 

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  • DEMONSTRATION _ DELIVERY HOLD - Customer Satisfaction Program 16S31 - Fuel Pump Control Module...pdf
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SHOdded

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  • PINPOINT TEST D TR SENSOR for 2010-2012 TAURUS SHO.PDF
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Guzzisvt

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I went to Ford and bought the start relay and start/stop relay. Took it out for 10 Mile drive and it restarted when I got home. Waited 10 minutes and it restarted, waited another 10 minutes and it restarted. Now I need to prove it. This means driving it as normal and carry my AAA card.
 

Guzzisvt

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Well, the relays didn't fix the problem. So I took off the air filter nozzle and put a light to the power wire of the solenoid. I have the light located near my windshield wipers so every time I hit the starter if it's getting power the light lights up. I haven't had it not start since I installed the light. Once it doesn't start I will determine if it's the starter or the signal to power the starter.
 

Guzzisvt

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Well, the relays didn't fix the problem. So I took off the air filter nozzle and put a light to the power wire of the solenoid. I have the light located near my windshield wipers so every time I hit the starter if it's getting power the light lights up. I haven't had it not start since I installed the light. Once it doesn't start I will determine if it's the starter or the signal to power the starter.
No start finally showed up and the light would light up, thus meaning the starter need to be replaced. I replaces starter and haven't had a problem since.
 

kryptto

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No start finally showed up and the light would light up, thus meaning the starter need to be replaced. I replaces starter and haven't had a problem since.
glad to hear the painful problem came to an end.
 
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