Drivetrain - Limp Mode, other than VSS what are the possibilities? | Page 2 | Ford Escort Owners Association (FEOA)
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Drivetrain Limp Mode, other than VSS what are the possibilities?

Discussion in 'Drivetrains' started by TrueRollers, Apr 9, 2013.

  1. denisond3

    denisond3 Moderator Staff Member

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    A lack of reverse lights would certainly make me suspect a bad 'neutral safety switch' and 'range sensor' - since they are in the same assembly. Lack of license plate lights on my Escorts has been just bad ground connections (in my hatchback) and a bad wire at the upper hinge point (with my 92LX wagon). As far as I know the license lights are just connected to the running light circuits - not associated with the backup lights at all. Though a bad ground connection near the rear lights could affect both.

    If you are in a pick-n-pull, and if you can harvest a set of the license light lenses and sockets, it might be a good idea. They seem to corrode a lot. Be aware the lenses for the license light are not the same on wagons as on the hatchbacks. I dont know about the sedans.
  2. zzyzzx

    zzyzzx FEOA Member

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    The license plate lights are unrelated and quite possibly bad due to dirt or corrosion. They can be cleaned. I cleaned mine with fine sandpaper and they can be lubed with dielectric grease. You have to take it apart (unbend to clean, then bend back to reinstall light bulb. You do not need to replace them!

    As for the neutral safety switch problem, I would be looking for a bad ground someplace since that could potentially cause all your problems.
  3. LariRudi

    LariRudi FEOA Donator

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    According to my 1994 EVTM wiring diagrams, they are separate; yes, you need a good contact in "REV" to get back up lights, so you're right there.

    Do your front and rear turn signals work? do your parking lights work both front and rear? The licence plate lights are on the same power supply. So if everything I've mentioned IS working, then the licence plate circuit is at fault; either not getting power, or NOT getting a good ground.

    [EDIT; ooops; I didn't see zzyzzx's post above when I wrote this; guess I've gotta "refresh" more often]

    Good luck,

    LarryR
  4. Intuit

    Intuit FEOA Member

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    Reverse lights, like the brake lights are probably dual-filament bulbs. This means your running lights can work and not your reverse and vice-versa. Be sure to check the bulbs before tearing into other parts/directions/connections.
  5. TrueRollers

    TrueRollers FEOA Member

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    Update... And if this worked i'm not going to complain. Got a used neutral safety switch/range sensor... donor was a 94 Tempo. So far, I have had no limp mode! I have discovered an open vacuum line... and broke another going to the EVAP canister (I think that's what it is) but I'll replace those later in the day. Let's hope later in the day it doesn't suddenly go into limp mode like when I did the VSS earlier in the week. The lights though... new problem, bad timing. Chaging the switch/sensor did nothing to fix the reverse lights. And oddly enough, when I put it in reverse my licence plate lights come on instead of the reverse lights... kinda weird. All the wiring in the trunk is VERY clean. All my other lights work fine. Nothing else comes on with the licence plate lights when i'm in reverse... weird shit. Gonna have to look at some wiring diagrams to figure this out. I know all the lighting is ground pulse controlled... now to figure out why the wrong ground is being grounded... You guys are the best! I hope in turn I can help someone with their escort!

    ** Another Update ** I have driven the car hard, gentle, long, short, fast, slow, all ways I can imagine, it has yet to go into limp mode. She may be fixed. Could have been bad connections, could have been bad sensor, could have been bad ground, don't know, don't care. All replaced and all fixed. I cheated and didn't put the bracket back on... grounded that one sensor wire directly to the transmission instead of the rusty bracket... Hell, maybe that's what fixed it. Now to figure out these lights... Again guys. Amazing, thanks sooooo very much!
  6. denisond3

    denisond3 Moderator Staff Member

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    I have the EVTMs for each of my Escorts; the wiring has small differences from year to year; plus they have different diagrams for the locations of components, connectors, wiring runs, splices and ground points - depending on whether your Escort is a 2 door, a 4 door hatchback, 4 door sedan or wagon, or a GT. So there isnt any point in my telling you where the grounds are depicted as per the EVTM for my 92LX wagon.
    But for sure there are some ground points and grounding splice points located in the tail end of the car. I also see one ground point by the fuel pump access lid below the rear seat cushion that is for things other than the fuel pump and sender!
    Ford uses a system of flat plastic 'connectors' that merely bring several wires together so they can be grounded; with the result that if the screw holding one of these to the body is loose - the items that should all be grounded - are all still connected to each other but NOT grounded.
    For that reason, lights that shouldnt come on may do so, and others that should illumin may not light; because they share a connection to a faulty 'ground'.

    This may not be useful. I cant help it. I got "data poisoning" from trying to follow circuits around in the EVTM.
  7. TrueRollers

    TrueRollers FEOA Member

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    Ok. Done. We can now close this thread! :woot: No more shifting problems! No more light problems! I believe there is some sort of switch in the trunk (or a weird grounding issue). I noticed when I open the trunk my licence plate lights turn off. Maybe it kills the reverse lights as well. Well, after a few precisely timed opening and shutting of the trunk, things all worked well and there hasn't been a problem since. +1 to everyone who helped me. I can't say it enough, you guys are great. I hope I can return the favor some time!
  8. Intuit

    Intuit FEOA Member

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    Pssst. I got a call from your trunk light problem this morning....
    [​IMG]
    TrueRollers likes this.
  9. TrueRollers

    TrueRollers FEOA Member

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    Guess what Sr. Intuit... LIMP MODE!!!! So this car hates me. All good until about 8pm this evening. Left my driveway and it jumped into limp mode. Long story short... Parking lights on = Limp mode, Lights off = No more limp mode. So what do these things have in common:

    1. Lamp switch in first position (parking lights only)
    2. Licence plate lights not working
    3. Reverse lights not working
    4. Car goes into limp mode.
    5. Slamming the trunk a few times, licence plate lights work again, reverse lights work again, and car doesn't go into limp mode while lamp switch is in first position... until later when the licence plate lights don't work and I have to repeat the slamming of the trunk...
  10. denisond3

    denisond3 Moderator Staff Member

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    What about when you have the headlights on? Is it still in limp mode (since the parking lights are still on?
    If I were in your situation, I think I would try removing both of the backup lamp bulbs, and see if the transmission would work normally with the two bulbs removed.
    Since I have never had your problem, nor do I recall anyone else ever having had it, I am just guessing, but.... . . .
    In the Electrical and Vacuum Troubleshooting Manual (EVTM) for my 94LX, on page 29-4 there is a note I never read before, adjoining the Manual Lever Position Switch (that is what Ford calls it and which in this thread we have been calling the "range sensor" and the "neutral safety switch".
    The note reads:
    ""This sensor incorporates a series of step down resistors which act as a voltage divider. The PCM monitors the voltage which corresponds to the position of the manual lever. This information is used in determining desired gear and EPC pressure. This sensor also houses the start circuits for the ignition system to allow the vehicle to be started in PARK or NEUTRAL. The BACKUP lamp circuits, which are closed in reverse, are also contained within this sensor.""

    So maybe the electrical problem that changes with trunk (hatch) lid closing and affects the backup lamps - is also affecting the 'voltage' the Powertrain Control Module is seeing when it is deciding to shift or ignore shifting.
  11. Intuit

    Intuit FEOA Member

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    Interesting Denisond3. Doesn't the PCM ground at that little node box on the negative battery cable ?
  12. denisond3

    denisond3 Moderator Staff Member

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    I just remembered: The location of one of the ground connections (for backup lamps and license lamps) at the rear of an Escort is in different places on wagons, sedans, and hatchbacks. On one of them its inside below the opening - inside of and behind where the license plate mounts. One the other body styles its either in the right hand rear corner (near where the rear lights mounts I guess) or its in the left hand corner back there. In each case you would likely have to pull out some trunk liner to see the connector.
  13. denisond3

    denisond3 Moderator Staff Member

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    Intuit: As far as I know, the PCM has multiple ground connections to the car; each of which is likely important for some function.
  14. TrueRollers

    TrueRollers FEOA Member

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    Ok. I really believe its fixed this time. This was something I could test. Found a bad ground wire. I took 1 inch sections of the wiring coming off my lights and wiggled them until I can get the lights to flicker. Found a bad spot. Unwrapped it and saw it was, what looked to be cut. So, I connect them, and BOOM, lights work. So, at this point, I'm fairly skeptical. There's NO WAY IN HELL this little 16 gauge wire is what was causing all my transmission problems. I mean come on, its 5 strands of wire and it's in the trunk... So I drive. Lights off and transmission is fine. Lights on and transmission is fine. Hmmm... still skeptical. So I drive more, thinking maybe I just need to give it time. Still no failure. Still skeptical, I mean, come one, it worked fine for almost two days, probably the same thing, right? So I get the bright idea, well, let's cut that wire and see what happens. Lights off, transmission is fine. Lights on... *PAUSE FOR DRAMATIC AFFECT*... INSTANT LIMP MODE!!!! Lights off, TRANSMISSION WORKS FINE!!! I'm still very skeptical at this point, so I pull over, reconnect the wires, and can you believe it... everything works fine with the lights on or off. I really can't believe that that little wire really caused all these woes for the last few weeks. Thank you Ford. Thank you for making this great wiring system that a reverse/licence plate light ground can COMPLETELY CRIPPLE YOUR CAR!!! In any case, she is good. Thank you to everyone, now lets hope this thread is actually closed. I will post a picture of the wire...
  15. TrueRollers

    TrueRollers FEOA Member

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  16. Intuit

    Intuit FEOA Member

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    I don't think Ford would design a circuit to operate that way.

    From what Den posted, it the sensor/PCM monitoring the reverse lamp circuit, got confused about the state of reverse and thus, quit shifting.

    Okay if the range sensor uses this *snipped* wire to monitor the state of the lamp circuit, why does switching the running lights on/off matter at all ?

    Suspect there is more than one weak ground. Note I said *weak* ground. When a circuit has insufficient ground path via it's normal designated spot and there are multiple, it's not unusual for it to "seek out" and use another.

    While the overt problem has been solved, I suspect there's something else, yet unseen, going on.
  17. TrueRollers

    TrueRollers FEOA Member

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    I would imagine because the reverse lights ground on the same wire. Connecting and disconnecting this wire also affects the reverse lights working. So by turning on the parking lights, it also turns on the licence plate lights, cause some sort of grounding issue, which apparently confused the hell out of the car. I hope there is nothing unseen going on, because I'm leaving tomorrow for Atlanta, and I really don't need my car braking down in BFE Kentucky, Tennessee, or Georgia...
  18. denisond3

    denisond3 Moderator Staff Member

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    Good Luck on your drive to Atlanta, and let us know if you have any more grief.

    You provided me with a nice new and unique problem - I hope we found the solution. And if it happens to another Escort owner - we have some background on it.

    From your photo I could imagine the vital wire got chopped when someone shoved an oversize item into the trunk and closed the lid on it; or some such event. From the rockauto catalog, the "range sensor neutral safety switch" (a.k.a. Manual Lever Position Switch) is the same in the 92 and the 95 LX. The EVTM for my 92 does not have the little note about the 'voltage divider' to sense shift lever position like the EVTM for a 95 does. I know the computer is different too. In 92 there was a trans control module by the driver's left toe, and the engine computer was called the EEC-IV. By 94 the transmission control functions had been incorporated into the computer board; which was now called the Powertrain Control Module.

    And for anyone who thinks this was a strange type of electrical gremlin - expect such issues if you ever buy a sporty Italian car. I had a 59 Lancia Flaminia, and 100% of the wires in the car's wiring harnessess were black with no color stripes. Totally unlabeled too.
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  19. madmatt2024

    madmatt2024 FEOA Member

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    Actually, I've seen wires in Fords just break like from use. It happened on the hatch harness in my wagon and several in the driver side door harness on my mom's old Taurus.
  20. TrueRollers

    TrueRollers FEOA Member

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    Well, it's been a week. We can say its officially been fixed. It really was that stupid ground wire. On an even more positive note. I suppose changing either the VSS or the Neutral Safety Switch or both has GREATLY increased my gas mileage. I made it from Dayton, Ohio to 20 miles from the Georgia border on 75 with one tank of gas!!! 390 miles give or take a few!!! Usually I'm filling up 20 miles into Tennessee.

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