Mustang New Engine Won't Start

Discussion in 'SN95 4.6L Mustang Tech' started by Flghtmstr1, Apr 2, 2012.


  1. Flghtmstr1

    Flghtmstr1 Member

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    I posted in my build thread, but I wanted to post here as well for more visibility. I tried to start the Mustang on Sunday and the engine didn't turn over. People outside the car said they heard a relay clicking when I turned the key, but nothing beyond that. Any ideas?
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  2. trinity_gt

    trinity_gt Advanced Member

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    Can you turn the engine over with a breaker bar on the crank bolt?
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  3. wmburns

    wmburns SN Certified Technician

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    I'm assuming this is a NO CRANK symptom.

    There is a round connector near the battery junction box. The wire is white with a pink stripe. Check to be sure this connector was not overlooked during the motor install.

    There are also a couple of smaller connectors near the battery that are easy to overlook during a motor install.

    You could also try jumping the main starter B+ terminal with the smaller starter solenoid terminal. This should make the starter kick in right away. Be sure the car is in neutral and the wheels blocked. This test will help confirm if the starter itself is good.

    Let's know if this is actually a crank with no start symptom.
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  4. Flghtmstr1

    Flghtmstr1 Member

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    Yes. I'm at work now, but I just called my friend (who owns the shop I'm using) and asked him to try to jump the starter solenoid with a screwdriver, and he said the starter engaged when he did so. So it sounds like the signal isn't making it from the ignition to the starter solenoid. To me, that means either the anti-theft system has been tripped somehow, the neutral safety switch isn't adjusted / working properly, or I have a wiring problem / short circuit somewhere.
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  5. Flghtmstr1

    Flghtmstr1 Member

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    Now that you're involved, I'm sure we'll figure it out. :hail:

    I'm pretty sure I connected that white wire before I put the battery in, as well as the other round connectors in this area. I'll have to double check tomorrow when I head back up to the shop. How many / which grounds need to be connected to the engine mounts? Right now, I just have a ground strap going from the chassis to the driver's side mount and a bracket supporting the trans cooler lines on the passenger's side mount. Should there be any additional grounds on those lugs?
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  6. wmburns

    wmburns SN Certified Technician

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    OK. For the 2001 MY, if PATS is activated, the symptom is crank with no start. So this is NOT a PATS problem.

    For the 96-98 MY, if PATS is activated, the symptom is no crank.

    Since the starter engages when the solenoid is jumpped, this proves there is enough ground. However, in answer to your question, there is only one ground strap from the left and motor mount to the frame rail.

    There is a starter relay in the battery junction box. It would be handy to know if that is the relay heard. If it is, this proves the problem is NOT in the neutral safety/clutch safety circuit and MUST be in the relay itself or the wiring harness.
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  7. Flghtmstr1

    Flghtmstr1 Member

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    Thanks. I'll check the relay and starter harness when I go to the shop tomorrow. Do you have (or know where I could find) wiring diagrams for the engine bay of a 2001 Mustang GT? It couldn't hurt to make sure every connector is plugged in.
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  8. Flghtmstr1

    Flghtmstr1 Member

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    The starter relay isn't clicking. It seems to be in good shape, though, as are all the fuses. I tested continuity between the fuse box and the starter and everything checked out. There doesn't seem to be a signal making it to the relay when the key is turned, though. I tried adjusting the shifter cable under the car and the neutral safety switch, but to no avail. Any more ideas?
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  9. wmburns

    wmburns SN Certified Technician

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    Pull the starter relay from the battery junction box.

    Test for +12 volts to the #85 (WH/PK) wire with the key in the "start" position.

    If NO voltage, the problem is in the neutral safety switch (NSS).

    Measure the resistance from the #86 (BK) wire to the battery negative. If the resistance is high (> 10 Ohm), the ground is bad/disconnected. If low, likely the starter relay is bad.

    NOTE: if the transmission DTR is not adjusted correctly, the transmission could be in gear and the NSS is actually protecting you from something bad. Did you remove the transmission? What did you do to re-establish and adjust the DTR to the correct position? Is this car a manual to automatic conversion?

    To test the neutral safety on an automatic, measure the transmission DTR key off resistance from 12 (WH/PK) and 10 (RD/LB). High resistance indicates the NSS is open. Try moving the DTR and see if this makes the resistance go low.
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  10. Flghtmstr1

    Flghtmstr1 Member

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    Based on the tests above, I'm inclined to believe the fault lies either with the DTR or the wiring from the DTR to the #85 pin on the starter relay. I tried to jump pins 10 and 12 to bypass the neutral safety switch, but I still didn't get it to crank. I measured the resistance between pins 10 and 12 and the #85 pin, and it came in at 79.5 ohms. If I'm not mistaken, the correct resistance should be less than 5 ohms, so if anything, that points to a problem with the wiring, correct? Anything I'm missing here?
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  11. Flghtmstr1

    Flghtmstr1 Member

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    As it turns out, it was a wiring problem of sorts. Apparently, Ford in its infinite wisdom decided to include two female connectors on the main harness on the firewall that could both accept the square transmission harness connector. I, of course, had it plugged into the wrong one. I only discovered this after ringing out the harness and determining that there was a fault between the transmission range sensor and the fuse box, disconnecting the transmission harness connectors at the firewall to see if I had continuity at the connector, and then noticing that there was another, identical female connector flapping in the breeze. When I plugged the trans harness connector into this "new" receptacle, it cranked.

    Does anyone know why Ford might have done this? I didn't read about it in any of the literature I have.
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  12. wmburns

    wmburns SN Certified Technician

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    Can you post pictures of the connector? What does the other square connector go to?
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  13. Flghtmstr1

    Flghtmstr1 Member

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    It isn't possible to take pictures of the connector because it's behind the engine on the firewall and there isn't enough slack to pull it up into view. I discovered it by feeling around back there, and it wasn't connected to anything. In case I wasn't clear before, there are two identical square 16 pin connectors on the engine harness side, and one of them has two or three wires coming out of it instead of a bunch. That was the connector the transmission harness was initially plugged into. When I discovered the other identical 16-pin connector with a lot more wires coming out of it, I swapped into that one, and the engine cranked.
    #13

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