Brake light switch question 1123

[Thumper580]

My first truck was a 998. Had to move the brake light switch a little to get the brake lights to work. On my 1123 the brake lights are not coming on so I checked out the switch. When you push the brake pedal the switch lever maybe moves a 1/16".... Couldn't see where or how the adjust it for more movement/throw... Any suggestions would be appreciated. Thanks.

 

[SmartDrug]

It’s an ancient design that should have been changed decades ago. You have two switches linked together- brake lights and torque converter unlock. I’ve found that with a handful of zip-ties holding the zig-zag tight, I can make it about 6 months before I need to replace/inspect whether or not the brake lights are working.

I’ll grab pics when the kids go down tonight.

 

[SmartDrug]

With some pressure on the zip-ties holding the unit together, it’s perfectly reliable until the plastic begins to age out. I would love a more reliable setup as I will occasionally realize one of the zip-ties broke and unless I’m really laying into the pedal, I’m not showing brake lights.

 

[Coug]

mine I just used a large pair of pliers and bent the "Z" rod until the lights worked properly.

 

[Thumper580]

mine I just used a large pair of pliers and bent the "Z" rod until the lights worked properly.

If you loosen the switch mounting bolts can the switch be moved rearward to preload the lever arm a little??

 

[Coug]

If you loosen the switch mounting bolts can the switch be moved rearward to preload the lever arm a little??

That's how it's supposed to be adjusted; loosen switch mount bolts and slide the switch one way or the other. The holes for the mounting bolts should be more like slots in which you slide the switch to adjust it.

I was along side the road during a convoy stop (we did a non-air brake vehicles run a couple years back) and didn't have the tools to slide it, just some pliers, which is how I figured out just bending the rod also works.

 

[Coonass77]

Not sure if it's just my bad luck or something more systemic, but I've had 2 m1123's that I wasn't able to adjust the switch (including bending the Z-bar) to a position where both the brake light and TC lockup switch would both activate when pressing the pedal. Both were solved by putting a couple washers on one side of the switch, between the switch and mounting bracket on the truck. The washers pitched the switch forward, thus moving the trip points more into the adjustment range of the switch. Once I did that, I was able to adjust the switch to a position that worked and haven't had to readjust either truck for 2+ years now. Not sure if this helps anyone, but just FYI if you can't seem to find the adjustment sweet spot.

 

[nairb]

Not sure if it's just my bad luck or something more systemic, but I've had 2 m1123's that I wasn't able to adjust the switch (including bending the Z-bar) to a position where both the brake light and TC lockup switch would both activate when pressing the pedal. Both were solved by putting a couple washers on one side of the switch, between the switch and mounting bracket on the truck. The washers pitched the switch forward, thus moving the trip points more into the adjustment range of the switch. Once I did that, I was able to adjust the switch to a position that worked and haven't had to readjust either truck for 2+ years now. Not sure if this helps anyone, but just FYI if you can't seem to find the adjustment sweet spot.

Could you post some pics of your set up? I'm having the same issue.

 

[papakb]

The standard brake lights draw some real power when you step on them and the switch arcs internally wearing the contacts down to the point where you have to adjust the switch position to get them to work. Because the original design is marginal and there's no free play travel adjustment on the linkage the brakes can start coming on before the switch travels enough to turn on the lights so you end up standing on your nose before the lights light. Change the switch and then change the brake lights to LEDs. They draw so little power your new switch should last forever.

 

[Coonass77]

Could you post some pics of your set up? I'm having the same issue.

Sorry for the delay.
Here's a pic of my m1165 with the switch shimmed. You can kinda make out the 3 washers between the switch and mounting bracket. The shim washers are on the side of the switch nearest to the hood of the truck.

 

[nairb]

Sorry for the delay.
Here's a pic of my m1165 with the switch shimmed. You can kinda make out the 3 washers between the switch and mounting bracket. The shim washers are on the side of the switch nearest to the hood of the truck.
View attachment 884226

Actually did this yesterday and it worked perfect, thanks for the tip!