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Dropped a donor motor into my '93 XLT, starting problems.

Discussion in 'Stock 1991 - 1994 Explorers' started by scoodidabop, April 11, 2013.

^^Searches ExplorerForum.com^^





  1. scoodidabop

    scoodidabop Active Member

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    So if I jump my relay on the inner fender with a screwdriver the engine starts up perfectly, so now what? The starter looked fine when I looked it over during the engine swap.

    My negative battery terminal has a bolt on it halfway down the wire that looks like it should screw into the engine block but the bolt is way too small to thread in. Does anybody have a wiring diagram for these parts? Next to that hole is where the starter connects to the engine block (right?) and it's cleaned up and screwed down tight but I had to add some washers to it since the bolt is too long for those threads. I'm thinking the negative connection to the block might be a crucial part here but what confuses me is that the engine still starts just fine despite this wiring conundrum using the screwdriver-to-relay method.
     
    Last edited: May 15, 2013
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  3. Maniak

    Maniak Moderator-Stock 91-94 Staff Member Moderator Elite Explorer

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    If you can jump the 2 big wires on the starter solenoid (on the fender) and it starts then you just issolated it to the "start signal" wire.

    When you turn the key to the "start" position 12v goes to a small wire than is plugged into one of the posts on the starter relay (IIRC, its the bottom one).

    You can eliminate the solenoid by putting the truck in the on position like you did when you used the screwdriver to start it but instead of jumper the 2 big wires just run a small wire from the positive side of the battery to the lower connector (small post) on the solenoid. If it starts then you're not sending the 12v start power to the solenoid. If it doesn't the solenoid is bad.

    There is a starter interrupt built into the explorers. If you have an auto trans its the neutral safety switch. If its a manual transmission its the clutch pedal switch.

    If you forgot to connect the neutral safety switch wire/connector to the trans it won't start.

    The clutch safety switch is under the dash so I doubt you messed that up (removing the jumper on an auto trans vehicle will also stop it from starting).
     
  4. Anime

    Anime EF YEAH!! Elite Explorer

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    The smaller bolt on the negative battery cable goes to the negative ground on the frame. The threaded hole for it is located on the outside of the frame, passenger side, just behind the inner fenderwell plastic.

    Having the battery, body, frame, and engine block all grounded with that one negative battery cable certainly helps with any electrical issues.
     
  5. scoodidabop

    scoodidabop Active Member

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    I will look into both of these issues this weekend and report back. Thanks fellas!
     
  6. scoodidabop

    scoodidabop Active Member

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    Still couldn't find the dang hole for the neg ground but I will check again.

    Used my volt meter on the relay at the fender. I'm getting 12v to one large post and to the small slip-on connector post. Now what?
     
  7. scoodidabop

    scoodidabop Active Member

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    Just had another thought; If I can start it by jumping the relay bolts together wouldn't that indicate a functional solenoid? Does jumping the relay bypass the solenoid somehow?

    The "s" wire and larger "I" wire both were just retested and have correct voltage. When I hit the key there is a single "click". If I duck down outside the door a little I can actually hear something that sounds like the starter begin to turn some. It seems more and more like this is could be a wiring issue. Is there a way to troubleshoot that?
     
  8. Maniak

    Maniak Moderator-Stock 91-94 Staff Member Moderator Elite Explorer

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    If you are jumping the 2 big wires @ the solenoid and it turns over then the wiring from the solenoid to the starter is fine.

    One of the small wires (S wire) @ the solenoid (on the fender) is the start "signal". When 12v is there it tells the solenoid to close and to send power down to the starter. You said you found the "correct" voltage but I don't know what you did or what you saw. You should not see any voltage on the S terminal @ the solenoid except while the key is in the "start" position.

    So, right now, either you aren't getting that signal to the solenoid OR the solenoid is bad.

    Do this test to figure which it is..

    Take the wire off the S terminal on the solenoid (@ the fender). Now take a piece of wire and connect it to the + side of the battery. Now take the other end and connect it to the S terminal on the solenoid.

    If the motor turns over the solenoid is good and you have another issue in the wiring between the ignition switch and the solenoid. If the motor does not turn over then the solenoid is bad.

    ~Mark

    EDIT: I forgot to say that the engine ground, at least on our '92, is bolted to a hole/boss on the engine that is near the passenger side shock mount.

    IIRC, its the boss on the side of the motor with the bolt in it, above the motor mount. Click on the pic to open it on flicker and then you can see bigger versions of the pic.
    [​IMG]
    engine-rebuild 019 by maniak_az, on Flickr
     
  9. scoodidabop

    scoodidabop Active Member

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    Thanks Maniak. I'll try that jumper wire and see what it does.

    In the pic the hole with the bolt in it is indeed where it seemed logical to attach the neg ground cable since the other wire bolted to the left of it just fine. The neg wire bolt is too small to thread into that hole though. I suppose the bolt could be switched out I just thought there was a hole nearby that was the correct size.
     
  10. scoodidabop

    scoodidabop Active Member

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    Nevermind on the grounding stuff I mentioned since I just rechecked it and it's all good.

    So I jumpered from the + battery post to the "s" on the solenoid and it did indeed crank the starter. The reading I get on the small wire with the key in "on" or "run" position is about 12V. Maybe this stupid solenoid/relay is bad!? I just installed it but damn, stranger things have happened! Reading the voltage on the "s" post on the solenoid when I hit the key it drops pretty fast and never really achieves 12V... I'll order a new solenoid and see what happens.
     
  11. wood1

    wood1 Well-Known Member

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    that fender mounted solenoid requires a good ground to operate, check that too.
     
  12. scoodidabop

    scoodidabop Active Member

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    Alright Maniak I finally made a jumper wire between the battery and the small slip-on connector post on the solenoid and it fired right up! So that means it's the neutral switch or ignition switch, right? How do I know which? BTW all issues are identical when the truck is in "Neutral".

    While I was at it I made a temporary replacement wire on all major wires leading to the solenoid, starter, and battery one at a time to isolate a faulty wire but they all checked out fine.
     
  13. scoodidabop

    scoodidabop Active Member

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    Since the NSS is tough to get to an looks like it's hooked up correctly I'm gonna try replacing the ignition switch first.

    My dad had a funny thought; He said, "Just run a couple wires to that solenoid and push you a push button on the dash! Make that sumabitch modern with a push button start!". Not gonna lie, I laughed at that one pretty hard.
     
  14. scoodidabop

    scoodidabop Active Member

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    UPDATE: Replaced the ignition switch, no change.

    Found out my voltmeter was giving some bad readings though and it seems the small wire on the relay/solenoid is only getting appx 5V when the key is turned. So that narrows it down quite a bit... perhaps just the wire needs to be replaced but man that's a tough wire to trace. Does it run all the way into the ignition switch!?

    ...that push-button idea is starting to look pretty good.
     
  15. Maniak

    Maniak Moderator-Stock 91-94 Staff Member Moderator Elite Explorer

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    I don't have a wiring diagram with me (at work) BUT, IIRC the actual start signal goes from the ignition switch (the electrical part, not the key part) and then runs "through" the clutch safety switch (or jumper) and then down to the transmission through the neutral safety switch and then up to that pin on the solenoid

    If that is true you can cut into the wire (just the insulation) and check if you have 12v on that wire when you turn the key. Check a wiring diagram before you do that as it has been years since I have had to mess with my NSS and trans harness.

    The reason I'm not saying to go directly to the push button is that you might have an issue with the neutral safety switch. If so the truck will think your in gear all the time which will at least piss off the 4x4 computer (won't be able to go into 4x4 low).

    I guess that is actually another test. Assuming you have push button 4x4, manually start the truck and then see if it will let you put it into 4x4 and then 4-low. If it won't it doesn't think your in neutral (or you have other, unrelated issues).

    While your under the hood, check that harness that goes from the transmission to under the hood. If it very common for the harness to come loose and then it ends up leaning onto the exhaust manifold on the drivers side. Usually when that happens it shorts out the TCC and the 3/4 solenoid wire which blows the EEC fuse but there are other wires in that harness.. and IIRC the nss wire is there.

    I'm somewhat sure that its the Red/Lt Blue wire and the Pink wires that are connected together when the trans thinks its in park and neutral. That is actually how our truck is currently setup. Since I don't have an a4ld anymore I jumped those 2 wires together so the truck thinks its always in neutral/park so it will start. I thought of wiring it correctly but since the Explorer isn't a DD anymore I don't mind it being able to start in gear.

    ~Mark
     
  16. scoodidabop

    scoodidabop Active Member

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    WOOOOHOOOOOOO!!!! Problem solved! ...mostly.

    As I was digging around behind the ignition switch to try and track where wires were connected I noticed this blue metal box that said FORD really big on it, tucked up nicely behind the dash. Upon closer inspection it read "vehicle security system"... ok, interesting. Then I saw that the largest of the 4 plastic plugs on it was freakin DISCONNECTED! ...wut? WHY!!??

    The previous owner didn't include a remote unlock key so I though my truck wasn't equipped. After I plugged the largest connector back in I knew why they unplugged it in the first place; the dang alarm stays stuck on. After popping the plug in and out 5 or 6 times the alarm stopped tripping and I was able to start the truck with the key! Success!!!! Luckily the wiring diagram is still legible on the back of the unit so I'm gonna try and jumper some wires together so the alarm system can remain disconnected.
     

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