Low voltage at the door lock solenoid?

Discussion in '60-Series Wagons' started by willflow, May 28, 2012.

  1. willflow

    willflow

    Messages:
    285
    Location:
    Prescott Valley AZ
    I did the door lock relay mod on my 87(88)FJ62 but still have 7.5-8 volts at the rr door actuator harness. The drivers door reads about the same too. The door will lock 98% of the time but doesn't want to unlock. If I pull on the knob just slightly it works. I have lubed everything up but that hasn't helped. The rr is the only door that is giving me fits, all the others work great. I even swaped out a spare actuator I have with the same results. Is it a bad wire going to that door? Why does the drivers door work fine with the same voltage? Where are the factory door lock relays? How about the harness going to the door, does it have a plug in it? I'm getting frustrated with this thing!
  2. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    I get the same low voltage at the actuator. Is this right?
  3. slcfj62

    slcfj62 SILVER Star

    In the diagram below, you can see the two Door Lock Relays for the solenoid for the rear hatch lock (called Door Lock Solenoid Back Door in the diagram). One relay is for lock, the other is for unlock. The power for the door lock solenoid back door comes through the 15A door fuse, through either relay, and directly to the either side of the solenoid. Lock is the Blue White (LW) wire and Unlock is the Blue Red (LR) wire. The White Black wire (WB) is ground. These colors are only valid in the wire loom up to the final connector before the solenoid and relays. Toyota switches wire colors after the final connectors for some reason.

    Below is a posting specifically about the solenoid and the relays. If the solenoid is good (ie you disconnected it and applied 12 volts across each coil and the thing actuates), then the problem is most likely one or both relays. Suspect the one mounted upside down.


    http://forum.ih8mud.com/showpost.php?p=4042079&postcount=32

    Attached Files:

    Last edited: Apr 30, 2013
  4. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    What about for the rear right and rear left doors?
    I'm getting a low voltage reading at the plug that goes into the actuator.
    Is this the switch contacts?
  5. all of my problems have been with the back door relays (next to the rear washer bottle), swapped them out with some other secondhand ones and was good for a bit then stopped working again, looking to replace with new ones or macguver stuff

    all my front doors are good just the bugger at the back persists to give me grief, still.....gong allright for 27 years old I suppose :)
  6. slcfj62

    slcfj62 SILVER Star

    Ah, the rest of the doors is another issue. It most often is the door lock switch, but can also be the connectors in the doors. In my case it was both.
  7. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    I cleaned the conta to in the master switch and it definitely worked better.
    3 of the doors didn't work at all before cleaning the switch and the driver door worked partly.
    After opening the doors and lubing the linkage, they worked better.
    There was still a voltage issue which cleaning the contacts helped, but its still not perfect.
    The passenger side front door does not work unless the engine is running.
    I am going to do the relay modification, but one thing I can't get past. The factory wiring seems old and I'm not sure the 12v positive lead that goes to the master switch is up to the task, even with the relay setup. If i was really motivated I'd run new positive leads from the battery to power the power locks and windows. But I'll try the relays without this for now.
    This is a common issue I think. Whether its the headlights, the cig lighter, windows, etc, everything seems to be very dim and low power. I would imagine it is old wiring and/or bad grounds.
    When I changed the battery ground cables, and added another to the body, the windows seemed to run faster.
    I need to find the other grounds and replace those. Something is not right and the grounds seem like the first step.
  8. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    After disassembling all of the doors and lubing the lock linkage I started getting frustrated.
    Was about to install the famous powe door lock relay mod. I opened up driver door and started to unplug the master switch when I realized that there was aftermarket wiring there. It seems that someone had cut into 2 of the wires that go to the power door lock plug, on car side. So they cut these 2 wires and bypassed them with smaller 14 gauge wires that are routed through door and back through vehicle somewhere.
    So they took a faulty design which already has too much resistance and cuts power down and added feet or yards of smaller gauge wire to cut the power down even more.
    I thought I saw a control pack under the dash that looks like it could be an alarm module.
    Anyway, I cut these wires off and restored the proper wiring and man, the power locks sound like they are going to shoot the lock throug the door.
    They are loud and now operate without fail.
    Feel foolish for tearing everything apart, but I suppose all the components needed some attention.
    So I will hold off on the relay mod for now.
    Thanks
  9. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    Im getting 6-7 volts at the rear right door actuator. This looks bad.
    Not sure why. I installed a Viper remote door opener which has its own relays.
  10. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    Another thing. I was testing the voltage at the wires running out of the master switch.
    They are 12+ volts when disconnected from the wiring that goes to the doors.
    But when connected, the voltage is 10 or so. I guess the draw from all of the actuators is pretty high to drop the voltage that much. And btw, I boosted the power source with a 10 gauge direct to batt positive lead to the switch assembly, so it is not the fusible links issue. Cant believe the voltage can be drawn down that low given the size of the power feed I have in there.
    Im wondering about the ground feed. There is a ground feed that goes into the master switch and that gets routed out to all doors. Given the small gauge used in factory wiring, not to mention age and corrosion, how can this 12 gauge single wire provide enough ground current to run all that distance to all of the doors and power them up?
    Is that why Im only seeing 6-7 volts at the door lock actuator?
    Im starting to think that even the relay fix is not adequate, mostly because it relies on thew factory wiring between the master switch and doors, not to mention the factory pos and neg feed to the master switch.
    Is the only real and permanent solution to run clean power feeds to each door and install relays at the door? The window relay fix installs relays at the door, but this fix does not deal with the issue of the quality of the power feed and ground.
    Im thinking of running clean 10gauge power feeds to each door, and possibly clean grounds to each door, and installing 2 relays in each door. The factory switch wiring will serve only to run the relays.
  11. Spook50

    Spook50 2014 Champs SILVER Star

    Messages:
    4,388
    Location:
    Spokane, WA
    Funny that this thread popped back up because I've been chasing the exact same issue with my RL door's solenoid. Low voltage, doesn't want to unlock, but will lock, HOWEVER, when the alternator is putting out the full 14V all the locks will pop perfectly. I did the relay mod myself a few years ago and everything had been perfect until this last fall. Figured it was the solenoid itself since it was just the one and it only had problems when unlocking, but newp.

    Lock switch and the connector in the door are both good in my case, too. I'm still chasing it and if I find anything out I'll be sure to post up.

    I like the idea of relays in each individual door like what Erik did with the window relay mod (which I still haven't done). It'd be great if a single PCB with compact relays (too bad solid state is so damn expensive still) could be built that would just plug right in to the lock solenoid and window motor plugs and just require new power and ground leads to be run. Wish I could design something up (be great for my engineering course too) but I won't have any free time for more projects at all in the foreseeable future.
    Last edited: Feb 1, 2014

  12. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    Yeah, similar to mine. I never did the relay fix, but the remote module I installed has relays. So when I lock/unlock with the remote, the power goes through relays, and when I use the switch, it goes through only the switch. Both ways have a fresh positive feed.
    all 3 doors except right rear lock and unlock fine.
    but the right rear only seems to work significantly when engine is running.
    i think the stock wiring is the issue. at nearly every location or accessory, the stock wiring shows weak power.
    headlights, dome light, radio, windshield washer.
    nearly every system has low power.
    I think the only permanent fix for the right rear door is to run power there and use a couple relays in the door.
  13. Spook50

    Spook50 2014 Champs SILVER Star

    Messages:
    4,388
    Location:
    Spokane, WA
    I think you're spot on about the inadequate (and now very old) wiring. That much resistance is going to cause significant voltage drop and loss of current.

    I'm thinking I should keep an eye on Digikey and Mouser for relays and connectors that would do the job in our doors...
  14. mrt6644

    mrt6644

    Messages:
    259
    Location:
    CT
    I'm struggling with how to manage the power situation in the FJ62. I don't want to create a total mess by recreating, poorly, the fusible links. But maybe if I bypass the bulk of the loads with new power and relays to some systems, I could lighten the load that the fusible links handle.
    I'm doing the headlight relay bypass today. I measured the voltage at the headlights with the stock wiring, without the headlight being plugged in and it was 10 volts! Batt voltage was 13 since it was plugged into charger. That's bad.
    Items that might be more difficult to cleanly bypass are windshield wipers, rear defroster, dome light.

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