Tow/Haul Switch

[cberentsen]

Tow/Haul switch inoperative.

99 GMC Sierra 1500 4x4.

Owners manual doesn't tell which of the three fuse blocks contain the fuse, perhaps combined with another wiring circuit? Neither does the Chilton's even address the Tow/Haul switch.

[Springthing]

I'm not even sure what switch you are talking about so I won't be of much help! But if all else fails grab yourself a meter and go from one fuse to the other checking for continuity on all the fuses.

[cberentsen]

I'm not even sure what switch you are talking about so I won't be of much help! But if all else fails grab yourself a meter and go from one fuse to the other checking for continuity on all the fuses.


Thanks Steve!

[cberentsen]

I'm not even sure what switch you are talking about so I won't be of much help! But if all else fails grab yourself a meter and go from one fuse to the other checking for continuity on all the fuses.


It's the button at the end of the shift lever that locks out overdrive when towing.

[Springthing]

ah! I know what you mean.. I don't have it so wasn't sure if yours did. :) Well, hopefully someone will come along and be able to give advice. I'd say if you have a meter just start going to town on checking for continuity. Should take you more than 5 minutes or so.

[trimhalifax]

You might want to check for broken wiring. Pop off the cover under your steering column and check the two wires near the shift lever. These have a habit of breaking due to movement of the lever.

[pmf608]

You might want to check for broken wiring. Pop off the cover under your steering column and check the two wires near the shift lever. These have a habit of breaking due to movement of the lever.

I agree on this one. They are two very small thin wire wrapped in a larger casing. I had to cut them to replace my shifter boot, and there is NO extra slack on them. i could see them breaking. I had to extend them to keep them from shorting when I shifted out of park once I fixed them. I would check this and if one or both wires are broken, I would solder in some extensions, seal them up, and you should be good to go.

[cberentsen]

Thanks to all of you!
cberentsen

[woodbw]

cberentsen did you find a problem with your wiring. My 06 just up an quit working over the winter. Only use it when camper is loaded and the switch did nothing.
QUestion for you is, when you switch on ignition does the light come on during the light test? My light does not so was thinking burnt out bulb, will road test to see if shift points are diff\rent soon.

Brad

[trimhalifax]

Mine only lights up when switch engaged,not at initial startup.

[pmf608]

I do not believe that the tow/haul is part of the light test. Mine does not come on, but I have rewired it three times now (bad fixes the first 2) and I know for a fact it works. If it does not work at all, start by checking in the steering column.

[Jimmiee]

cberentsen did you find a problem with your wiring. My 06 just up an quit working over the winter. Only use it when camper is loaded and the switch did nothing.
QUestion for you is, when you switch on ignition does the light come on during the light test? My light does not so was thinking burnt out bulb, will road test to see if shift points are diff\rent soon.

Brad

Brad,

The quick and easy way to check your switch is with a scanner. You can see if the switch is working and if the signal is reaching the PCM. All this without messing with any tools or taking anything apart.

[John W]

The best way I found to check if the wires are broken is to hold the tow haul button in while shifting from park all the way to low gear. If the wire is broken the light will usually come on when this is done. Had to repair mine yesterday. About 45 min for the repair.

[woodbw]

John what id the wire look like. Tried like you said and I got my light to come on also. When I peeled back the shifter boot the only wire I can see is a large orange one. Should have at least three wires I thought. One for UP/DOWN shift and one for tow/haul.
Could you explain your fix.

Brad

[John W]

John what id the wire look like. Tried like you said and I got my light to come on also. When I peeled back the shifter boot the only wire I can see is a large orange one. Should have at least three wires I thought. One for UP/DOWN shift and one for tow/haul.
Could you explain your fix.

Brad

Brad, sorry I didn't see your post untill today. What I did was tilt the steering wheel all the way up, then took two thorex screws out of the bottom cover of the steering column just below the steering wheel and and removed the cover. Then you can really see what you have to work on. What looks like a large orange wire is only a tube covering the two wires. Both wires are white and very small. I had to slit some of the orange covering to find the break. On mine it was very near the second rubber grommet from the shift lever. Hope this helps. Let me know how you get along.

John W

[Mattdtrue]

I have a question to add sometime mine comes on but I have to press it several times is thus causes by the short wires loose connection ? Another issue it sometimes clicks in while I'm moving down the road in mid haul,will this damage anything ?

[John W]

I have a question to add sometime mine comes on but I have to press it several times is thus causes by the short wires loose connection ? Another issue it sometimes clicks in while I'm moving down the road in mid haul,will this damage anything ?

I would say the first thing is check the connections where the orange wire plugs into the harness, if the plug is ok and you have no other transmission problems get another tow haul switch and replace the original. You might be able to pick one up at a salvage yard. And don't forget, when you have eveything apart check your wires before installing the new one.

John W