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Limp mode e4od

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Selahdoor, Sep 3, 2019.

  1. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    92 f250 7.3 na e4od

    I believe the trans is in limp mode.

    "OFF" light will light up and stay on, steady, if you push the button, first thing.

    But it starts flashing, and continues flashing for the rest of the time the truck is running, as soon as you start to actually drive.

    Revs way up, before it shifts.


    Now, the question...

    I have to drive this to the shop.


    Of COURSE I'll baby it. And yes of course it would be best to trailer it. Don't be captain obvious. LOL

    Aside from that...

    What speed should I not exceed? Etc. Are there specific instructions for this scenario?
     
  2. saburai

    saburai Full Access Member

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    How far? What speed?
     
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  3. 79jasper

    79jasper Chickenhawk

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    Yeah, throw it on a wrecker.... ;poke

    Sent from my SM-N960U using Tapatalk
     
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  4. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    That's what I asked!!! ha ha ha LOL

    About 16 miles.

    And I have two choices.

    One... the highway. Highway speeds, or constantly pulling over to let others pass.

    Two, the back way. Slower speeds, but LOTS of very steep and curvy terrain.

    Thank you captain obvious! LOL
     
  5. saburai

    saburai Full Access Member

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    If you decide to drive, take the highway. Right lane, flashers on, 45-50 3rd gear.
     
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  6. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    Thank you.

    THAT... Is doable. :D And it won't be unusual around here, to be going 45-50 in the 60mph zone. LOL But I'll pull over often to let people pass. (2 lane highway.)

    I have no idea if it will even go to 3rd gear. I haven't yet had it off our gravel back road. Only gotten up to maybe 20mph.

    Who knows. Maybe taking it out on the highway and getting into 3rd might do it some good...

    Think I'll check the trans fluid one last time, before I actually get on the highway, though.
     
  7. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    Thanks guys.

    This is not as urgent as I thought it would be. They can't get me in the shop until next monday.

    I might even take it out on the highway a little bit, before then, just to see if it improves any, after actually running for a bit.

    Thinking, just like the IP, maybe just sluggish until it gets the kinks worked out? IP is working beautifully now. And man you shoulda seen the crud in THAT thing!
     
  8. snicklas

    snicklas 6.0 and Loving It!! Staff Member

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    Ok, I know you have a couple threads on this, but let’s cover a few easy things, and have it all in one place.

    1. Does the tachometer work, and appear to be fairly accurate? Meaning, at idle is indicating the 600-700 RPM it should, it’s not reading zero until you give it some throttle.

    2. Does the speedometer work and appear to be accurate? On this and the tach I’m not looking for “surgically correct”, but if you’re going 10 is shows about 10, not won’t move, or shows 50.

    3. When you first started the engine, and the light is off, it’s truly off, not dimly glowing? I don’t think this is the issue since it will blink and stay bright solid, but want to check. Very dim all the time is a power supply to the TECA (Transmission Electronic Control Assembly).

    4. Do ALL your brake lights work correctly? All 3 bulbs, the stop/turn/tail and the high mount in the back of the cab? They are not LED bulbs either? They don’t do anything “funny” electrically? Like make other lights light up when they aren’t supposed to. That TECA passes a small contol current through the brake light circuit, and any issues there can cause limp mode.

    5. The FIPL (Fuel Injection Pump Lever (throttle position sensor)) on the drivers side of the pump is plugged in? Have you check the voltage from it? Center pin should be smooth from idle to WOT. It has a specific range, but right now I wanna make sure it just works.

    6. Have you inspected the electrical connector on the passenger side of the transmission to the solenoid pack? It’s behind a heat shield (yess it needs to be there, the exhaust is very close and can melt an unprotected plug. Make sure there is no transmission fluid in the connector. If so, that can cause this.

    I’d say more than likely it’s an electrical problem, since it starts as soon as you move, and that you can get the OD OFF to,work until you move.

    The E4OD need a good tach signal (from the tach sensor on the IP gear cover), a good speed signal (from the VSS (vehicle speed sensor) on a brick, a pickup in the speedometer cable, on an OBS in the rear differential), a good throttle position signal (From the FIPL), the gear selection (From the MPLS (“neutral safety switch”) on the drivers side of the transmission) and it must be able to “communicate” wither the solenoid pack in the transmission.

    There are some other things, but if those “basic” things don’t work right, then it can cause limp mode.

    I would drive it least as possible, as limp mode is a get it off the road safely thing. I understand you need to get it to the shop, but I would make it as direcr and “short” as possible.
     
  9. trackspeeder

    trackspeeder Stone crusher.

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    Driving it will not make it better. Leave it parked until you are ready to bring it to a shop.
     
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  10. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    PERFECT!!!

    I have some answers right now. I will check some things, and have other answers, later.

    First, thank you very much for going to the trouble!!

    And thank you Steve Phillips for sending me all the info!



    1. tachometer actually appears to be pretty dead on. Yes, 600 to 700 at normal, warmed up, idle.

    2. No way I can be positive about the speedometer. I have never had it over 20. But it does appear to be ok.

    3. a.) If I disconnect the batteries when I come in for the night. Then when I start it in the morning, the light is completely off. No dim glow. Pushing it, turns the light on, solid. Then any driving causes it to blink.

    I was disconnecting the batteries, because there was a parasitic drain. I think that drain was caused by the electric trailer brake assembly. Which I have now removed, and suddenly my 'wait to start' light, and my dome light, both work.

    b.) If the batteries are left connected, then when I start it again in the morning, the off light is still on. Solid. (unless I turn it off.) But starts to blink again, when I begin to drive.

    4. I have not checked the light over the cab. But the regular brake lights do work. No LEDs. (Backup lights are LED, though.) The brake light on the dash comes on, and stays on, most of the time. Only a time or two where I have seen it go out.

    The brake pedal is sticky. It stays down, further than it should. Never returns all the way to the top. Even when I pull it up with my toe. And this DOES effect the brakes. The truck moves a lot more freely, when I pull that pedal up. That is going to be looked at by the shop, next week. I'll probably have them do a complete brake job. I hate brake work.

    5. FIPL is connected. And it does work. I don't think the voltage goes as high as it is supposed to. Basically, I couldn't get the range I needed. Go low, it won't go high. Go high, it won't go low. I'll probably just have the shop replace, and adjust that, next week. If I don't replace it myself before then.

    6. No. I have never looked at that. I will get to that as soon as I am able. And I will report back what I find.

    And that synopsis is exactly the sort of 'comprehensive understanding' I was hoping for. Thank you!

    Also, I was having the same thought, when I started this. It would be good to have all the information in one place.

    Now I have work to do, a plan to get it done, and a whole lot less confusion about what I am doing. It'll probably be a few days. I have to take care of other things in life. But this may get-er-fixed, even if I have to buy parts. Or at least I may better know what to have the shop look at.
     
  11. BeastMaster

    BeastMaster Full Access Member

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    Please pull the codes first.

    When I first got my van, it went from occasionally screwing up to consistently terrible. To the point I was ready to replace the controller with switches and relays, and drive it like a manual.

    The controller kept complaining about it's VSS. I ended up replacing everything in the VSS circuit.

    My problem was a fault in the PSOM, fixed by replacing with another off of eBay. The problem was obvious once I was on the PCM's VSS input line with an oscilloscope. I had nothing even remotely looking like a pulse train there.

    Many things can confuse the hell outta your PCM. And most of them are really cheap to fix.
     
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  12. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    Update. Checked the light over the cab. Bulb was burned out. Changed it. But I don't see how this would affect anything. The only time that light comes on is if you turn on the dome light using the headlight switch.
     
  13. 79jasper

    79jasper Chickenhawk

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    The high mount brake light, not the cargo lights.
    That circuit is monitored by the TECA. Theoretically should disable cruise control as well.

    Sent from my SM-N960U using Tapatalk
     
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  14. ifrythings

    ifrythings Full Access Member

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    92 didn’t have the high mount brake light, that only came out in 94.
     
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  15. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    This is probably the reason that the brake light on the dash is on.
     
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