hot wiring a wiper motor

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mancinator

mancinator

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Jul 27, 2003
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Pitt meadows BC
Hi everyone....long time member, haven't posted in years. If you want to skip the fluff, just go straight to the last line to see if you can help me out....thank you in advance.

Have a mostly 74ish FJ40 that I resurrected out of a farmers field some 8 years ago. Everything has been a fun challenge until now. alot of cleaning, grinding, painting, welding, axles, spring over, engine tune, new cage...basically remodeled everything, but I am not skilled enough to make it pretty, I am not, nor is my franken-cruiser a candidate for restoration, it is just a fun weekend cruiser for myself and the family to enjoy bombing around in. It will always be the ugliest unit at any club meet, which suits me just fine.

Suffice to say, the wiring was an absolute disaster when I got it, with splices and bad grounds as far as the arm can reach. I managed to get it running reliably and had no issues for a few years while I enjoyed blasting around and was able to work on other issues.

One evening, about a year ago, my lights stopped working and it was nighttime and I started looking around for the bad ground that was causing the issue. Eventually I found it buried somewhere under the dash, but replacing one issue for another, my windshield wipers stopped working, along with my front blower (heat).
I have looked at wiring diagrams and traced wires as far as I can reach and see....everything worked as it should before I started trying to sort out the light issue. I have clearly unhooked a bad splice or a ground somewhere and I will never find the one issue that I need to reconnect. I have realized that now....after prob 100 hrs of trying different things, multimetering everything etc I have given up trying to fix some ancient splice....on my previous LC I had similar issues and just ripped every wire out and put in a new harness. Had it start to finish done in a weekend, but that was 25 years ago and I had nothing but time and supple joints back then....now I dont know if I am up for a full rewire, altho the garage rage has def pushed me to the precipice of doing so.

Ok, enough pre-amble....I am wondering if anyone has the "cheat code" that can explain or show me how to hotwire my wipers off a simple toggle switch. I have tried running 12v power to the switch, to the motor itself, grounding it various ways...it seems I have no power going to the original switch either, and no power going to the motor when using the existing wiring setup, so I am looking to just do it direct. I previously had to do this with my old 67 and it was fine, it had the 2 individual motors and it was a snap. My current wipers are top mounted, with the main motor on the passenger side and the smaller motor driver side, connected via thick cord. All wiring to the pass side and a 4 point plug. I have continuity thru everything but the motor does not respond when I direct wire 12v to it. I am either doing something wrong or the motor coincidentally died in the last year while I have been trying to get it going. I am certain the motors work, I am just not providing the power source correctly.

Edit. I forgot to mention…one of the biggest issues is the stock harness itself is so goddang short, it barely reaches the switch as it’s, so I have very little wiggle room in there to see what the problem is. A lot of telescoping mirrors, angles and flashlights to source things out. Wish there was another foot of line on it but it is what it is.

If you skipped to here, All that to ask, if anyone has a wiring diagram or a blue collar explanation of how I can hardwire my wipers off a toggle switch. I can attach photo's if required.
 
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The stock switch
The wiper motors
The night mare

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It may be easier for you to create a wiper only harness and abandon what is inside your existing harness if you think it is failed. There are a group of bullet connectors under the dash above the fuse box area that connect to the wiper windshield harness that you could connect to. Run +12 to the blue wire (with appropriate fuse) and make a short harness from the bullet connectors to your wiper switch. I think that would be much easier than trying to hotwire with toggle switches.
 
I'm currently working on my wiper motor also. Mine is a 76n2ith bottom mounted wiper, so I can't directly help you, but it seems if you don't have 12v at the switch or at the motor, that is a 0lace to start. The motor is supposed to have constant 12v,if it is like mine. The plug at the motor has 4 wires. One 12vthat is switched to the ignition circuit. The other 3 are switched grounds. One for slow speed, one for high speed, and one for the park circuit. Yours should be similar. Hope this helps.
 
Good for you. I’ll take a fun weekend cruiser for my family (which is what I have) over a show queen any day.

I’ve got a 67 and a 78, so you’re in a bit of a grey area for me with a 74 with an oem motor, but I’ll try to help.

Power comes from a Blue (L) wire from the fuse panel (wiper fuse). That wire is spliced and the L continues onto the washer reservoir, and to the B+ post on the wiper motor itself. This is your 12V+.

To test it, use a test light or multimeter to make sure that post has 12V+ with the ignition on.

If you’ve got power there, your issue is the ground. Ground comes from either the blue/ black, blue/ white, or blue/red wires directly from the switch.

The switch itself has 3 positions Off/ Park, High, Low.

In off position, blue/ black (LB) is grounded for the park position. When you pull the switch to position 1, it grounds the blue/ white (LW) for low speed. Then position 2 grounds Blue/ red (LR) for the high speed brush.

My guess is that when you solved your ground issue before, you disconnected the ground white/ black WB) for the wiper. Based on the diagram, it appears the wipers share a ground with the headlights. So there’s a WB wire that goes from the switch into the harness, and is spliced into a WB somewhere (sorry, not sure where). If that wire from the switch isn’t grounded, your switch isn’t actually switching to ground which means the motors won’t do anything.
 
Engineer8000 said:
It may be easier for you to create a wiper only harness and abandon what is inside your existing harness if you think it is failed. There are a group of bullet connectors under the dash above the fuse box area that connect to the wiper windshield harness that you could connect to. Run +12 to the blue wire (with appropriate fuse) and make a short harness from the bullet connectors to your wiper switch. I think that would be much easier than trying to hotwire with toggle switches.
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@mancinator this is what I did until I rewired everything. I didn’t even know my original wiring was under the dash, so I just ran a new sub harness. Coolerman makes this subharness. Or I can send you a foot or so of wiring and bullet connectors if you need it to extend your harness of the LB, LW, LR that I pulled off. It’s just sitting in my excess wiring box.
 
I am soo rusty, I cant believe the solution was soo simple. I spent soo much time tracing schematics trying to find the correct junction, I should have abandoned saving this existing harness given all the splices in it...with the pointers given here, I was able to get the thing hot wired first try. I spent soo much time trying to run everything thru the stock switch, I never thought that the switch might be malfunctioning. In any case, I will be able to get the wipers going on one speed at least, which will be fine as its a fair weather rig anyways. I will do as recommended above and just bypass the existing harness, create my own for the circuit, and maybe just maybe ill be able to salvage the existing switch, but at least for now, if i have to, a toggle will do just fine.

Thanks fellas
 
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