GEAR VENDORS TROUBLESHOOING HELP NEEDED

[78F150SUPERCAB4X4]

Cubey--Good thought, might have to try that after I do the testing the guys in this thread have suggested. But since I don't get home from work until after dark, it might not get done until this weekend.

 

[Olds64]

Are your battery cables in good condition?

 

[78F150SUPERCAB4X4]

Olds64--I believe so. Why?

 

[Olds64]

I ask because crispy or burnt cables can lead to poor grounding which; of course, is notorious for causing drivability problems. Just brainstorming.

 

[78F150SUPERCAB4X4]

Olds64--Yeah that makes sense. I actually made my own cables out of some 00 welding wire. Shouldn't have any problems with the cables.

 

[78F150SUPERCAB4X4]

Ok guys, I have an update. So I flipped the on/off power switch on the dash switch and nothing on the control box changed. There's still just one light lit up on the control box, which I believe is just the light indicating there's power to the box because when I unplugged the fuse, that light went out. So the control box is getting power. So when I flipped the switch on the gear shift, nothing happened on the control box (no lights other than the power light) and the red light on the dash switch did not come on. I also unplugged the wires that are plugged into the control box and plugged them back in and still nothing.

I tested the ohms on the ground and I'm getting 1.4 ohms. One of you guys said I don't want anymore than 10 ohms so it looks like my ground is good. I also tested the volts on the gear shift switch. I turned it on and it's got 12.78 volts. The only thing I didn't get a chance to test for power is the dash switch because I would have had to removed the dash panel to get to the mounting screws to remove it from where I have it mounted on the dash to be able to get to the electrical connections. But since I haven't touched anything on this system prior to when it suddenly stopped working, I assume the dash switch is getting power. But if you guys need me to test it, I can do that another day. It's currently 19* outside, it's getting dark and I'm freezing so I thought I'd skip that test for now and let you guys know the results of the other tests.

So what do you guys think? Do you think it's the control box or the dash switch? Or something else? Are there any other troubleshooting tests you want me to do?

Thanks for the help.

 

[K-nite]

Have you checked the speed sensor and its wiring? Didn't see that mentioned yet. And, no I don't really know how to test the sensor itself, maybe spin it with a drill and hook up to multimeter. If I recall correctly the sensor connections at the control box are similar to a phone plug (landline), could be bad connection. Good luck.

I'm not an expert, but I installed one on my brother's truck 20 years ago. The control box is sort of like a Murphy switch or safety switch. It can have power but you can't shift until certain criteria are met, auto or manual shift mode, 4wd drive lock out and 20-25 mph forward speed. Once those are met it sends power to the shift solenoid on unit. The gear vendors can work with just a single power switch to the solenoid, but then the driver is responsible for the safety of the driveline. If you run it below 20-25mph you'll burn up the internal clutch pack because not enough oil pressure in unit, bad. With 4wd lock out the front and rear axle will have different effective drive ratios, bad. Auto and manual shift mode you don't want the unit shifting automatically with a manual transmission as you'd have a huge driveline shock, bad.

 

[78F150SUPERCAB4X4]

K-NITE--I have not tested the speed sensor, but I did unplug and plug back in all the wires going to the control box and that didn't fix the problem. The problem seems to be that the red light on the dash switch won't come on for some reason. When it does come on, the GV will shift. I can sit in the driveway with the key on and flip the toggle switch on my gear shift and the red light use to come on, but now it won't come on at all, even when driving down the road. But like I said, when the red light is working, it will shift and the green light on the dash switch will come on. I'm not sure that the speed sensor has anything to do with the red light coming on or not since the red light will come on with just the key on (when it's working). So I'm not sure what triggers the red light on the dash switch to come on. I suspect that's where I need to look, but I don't know what to look for. Do you know what makes that red light come on when I flip the toggle switch? The toggle switch is getting 12.78 volts, so I know what switch is working. Could it be the dash on/off switch? I might just have to take the dash bezel off so I can remove the dash switch so I can inspect the wires. Other than that, I have no idea what to look for or what to test.

 

[K-nite]

I'll have to check out my brother's truck tomorrow for a refresh. No promises on any good ideas, though.

 

[BlindAmbition]

Here is a PDF with diagram. The GearVendors box itself is a mystery box as far as how it works or what it does, though this diagram hopefully helps. It is a for a 4x4 manual truck, should be similar.

That diagram shows a manual/auto selector switch. Ensure that switch is working by checking continuity and switched to the correct position.

 

[Olds64]

Thanks for posting the diagram. Hopefully the OP's GV unit is setup that way.

 

[K-nite]

You said you had voltage to the switch on shifter. How about through the switch, continuity? I might be splitting hairs here with your wording, sorry.

 

[78F150SUPERCAB4X4]

BlindAmbition--Thanks for posting that diagram. So it looks like mine is wired the same way, with one exception. I don't have a 4x4 lockout wire plugged into anything because my truck is a 78 and the tranny &/or transfer case doesn't have any electronics on it to plug the 4x4 lockout wire into. So that wire is not being used. But it's been working fine for 8 years so I assume it's not an issue. A couple years ago I did accidentally try to shift it into OD a couple times when I was using the 4x4 and it kicked it out of 4x4. Isn't that what the 4x4 lockout is supposed to do? If I don't have the 4x4 lockout connected, I wonder how it kicks it out of 4x4?

K-Nite--So when I tested for voltage on the gear shifter switch, apparently I did it wrong. There's a red & black wire on the switch and I thought the black wire was a ground, but I was told that it's not, that it's also a power wire. So when I tested it, I put the black lead from the multimeter on the black wire on the switch & the red lead on the red wire and turned the switch on and got 12.78 volts. But I need to redo this test with the switch on and off because apparently the black wire has voltage also. So I need to redo this test and test the wires individually. I also need to test the dash on/off switch, but I need to remove the instrument bezel to get to the mounting screws to remove it from the dash. I'll work on that sometime this weekend.

 

[IDIBRONCO]

Plus you want to make sure that you have a good ground wherever it is at.

 

[78F150SUPERCAB4X4]

Idibronco-- The ground was the first thing I checked. It's only got 1.4 ohms and the wire is on bare metal. The ground seems to be good.

A couple guys mentioned to check continuity. I know this may be a dumb question to most, but I'm not too knowledgeable about electrical stuff. How do you check continuity and how do I set up my multimeter? What setting do I put my multimeter on?