Cruise Control Troubleshooting

Joined
Jun 19, 2016
Messages
12
Location
San Diego
Hello all,

I'm troubleshooting the cruise control on my 1994 Land Cruiser. I've searched the forum for great tips and am at the point where I have extracted the stored code in the cruise control ECU.

The stored code is a 12, which points to three possibilities according to the FSM:
1: the actuator itself. I have disassembled it and it looks great,. practically new. I've assembled and reinstalled it.

2: the stop switch. This is where I'm at currently. I've readjusted the stop switch several times in varying positions. I have removed it and removed the blue cover which is easily removed by bending two metal tabs. I blew compressed air through every crevice I could, reinstalled it, and still have an issue.

I'd hate to purchase a new brake light switch just to have the problem lie elsewhere. Has anyone disassembled the switch completely? It is held together by the metal casing having it's edges bent over the black plastic body. This seems more difficult to remove riskier. The black plastic body looks to be easily damaged.

3: if the above checks out okay when I figure out how to check it, the last step in the FSM is the cruise control ECU being he culprit. It is also very possible the the wiring between the ECU, actuator, and/or stop light switch is damaged as well and I will check that eventually too.

Anyone have any input as to completely disassembling the stop light switch?

Thanks,
Jon
 
Joined
May 26, 2005
Messages
8,265
Location
Phoenix
Website
www.tralaz.org
Hello all,

I'm troubleshooting the cruise control on my 1994 Land Cruiser. I've searched the forum for great tips and am at the point where I have extracted the stored code in the cruise control ECU.

The stored code is a 12, which points to three possibilities according to the FSM:
1: the actuator itself. I have disassembled it and it looks great,. practically new. I've assembled and reinstalled it.

2: the stop switch. This is where I'm at currently. I've readjusted the stop switch several times in varying positions. I have removed it and removed the blue cover which is easily removed by bending two metal tabs. I blew compressed air through every crevice I could, reinstalled it, and still have an issue.

I'd hate to purchase a new brake light switch just to have the problem lie elsewhere. Has anyone disassembled the switch completely? It is held together by the metal casing having it's edges bent over the black plastic body. This seems more difficult to remove riskier. The black plastic body looks to be easily damaged.

3: if the above checks out okay when I figure out how to check it, the last step in the FSM is the cruise control ECU being he culprit. It is also very possible the the wiring between the ECU, actuator, and/or stop light switch is damaged as well and I will check that eventually too.

Anyone have any input as to completely disassembling the stop light switch?

Thanks,
Jon
A documented problem is a depression or hole in the pad that the brake switch contacts, which then doesn't fully depress the switch. I was able to rotate that pad so the depression wasn't in line with the switch, as a 'temporary' fix that I haven't had to improve on as of yet. A part of my diagnosis was pulling up on the brake pedal when trying to engage cruise control- when that was effective, I knew the problem was related to that switch not being fully actuated. Another possible culprit is the absence of the brake pedal return spring.
 
Joined
May 20, 2009
Messages
2,207
Location
Canby Oregon
While driving lift the brake pedal with you left foot, and see if the CC works, I have this issue with mine, and one day I will buy a switch :rofl: :rofl:
 
Joined
Jun 19, 2016
Messages
12
Location
San Diego
A documented problem is a depression or hole in the pad that the brake switch contacts, which then doesn't fully depress the switch. I was able to rotate that pad so the depression wasn't in line with the switch, as a 'temporary' fix that I haven't had to improve on as of yet. A part of my diagnosis was pulling up on the brake pedal when trying to engage cruise control- when that was effective, I knew the problem was related to that switch not being fully actuated. Another possible culprit is the absence of the brake pedal return spring.

Yes, I see what your are saying. I've adjusted the switch back and forth with no luck. Interestingly, the rubber pad that comes in contact with the switch doesn't really have much of an indentation.

I found another thread where someone actually took the switch apart and you can see the contacts for the cruise control section of the switch and you can see how they are slightly worn and bent in a way to prevent contact, which means the cruise control ECU is constantly seeing a cancel signal from the brake light switch.

If I can find a way from opening the switch up without damaging it, I am confident I can clean and adjust these contacts.

Pictures courtesy of Inushuk.

20220704_134753.jpg


20220704_134831.jpg
 
Joined
Dec 10, 2007
Messages
9,127
Ditto what others have said; if the cruise control works while pulling the brake pedal up with your foot the problem likely isn't in the switch.

Was any work done recently on the vehicle, engine bay, ground wires disturbed, burned out rear tail lights, LED brake lights installed, shorted wire??

One issue I ran into a few years ago when my cruise control would disengage when I turned on my headlights. This started immediately after replacing a rear tail light with a new incandescent Sylvania bulb (not LED). When I removed that bulb the cruise control again worked normally. I tried another new bulb from the package of two, same thing. Then tried a different brand bulb (not Sylvania) and no issues. So maybe I just got a bad set of bulbs, IDK.
 
Joined
Jun 19, 2016
Messages
12
Location
San Diego
Ditto what others have said; if the cruise control works while pulling the brake pedal up with your foot the problem likely isn't in the switch.

Was any work done recently on the vehicle, engine bay, ground wires disturbed, burned out rear tail lights, LED brake lights installed, shorted wire??

One issue I ran into a few years ago when my cruise control would disengage when I turned on my headlights. This started immediately after replacing a rear tail light with a new incandescent Sylvania bulb (not LED). When I removed that bulb the cruise control again worked normally. I tried another new bulb from the package of two, same thing. Then tried a different brand bulb (not Sylvania) and no issues. So maybe I just got a bad set of bulbs, IDK.

Thanks for the insight. My cruise control has never worked, and messing with the brake pedal has never done anything.

I do my own work on the truck, but don't know what was done prior to me getting the vehicle. It seems like it had a amplifier installed (and removed) before I bought it.

I do also have an issue where the gauge fuse will blow if the transmission is in 2nd hear and the shifter is not touched. I believe this is due to bad transmission connectors from what I've researched on the forum.
 
Joined
Jun 19, 2016
Messages
12
Location
San Diego
SUCCESS:

After having the truck for 5 years (but neglecting to tackle this particular problem until last week), I finally have cruise control.

The problem was indeed the stop switch. I tested it with an ohm meter, took it apart VERY carefully, saw the areas that were worn, and added some solder, reassembled, and reinstalled the switch (this was just to make certain it was the switch only and not also the cruise control ECU).

After going on the test drive, it was actually a shock not to see the green CRUISE light flash 5 times. Everything worked, brake switch and other cancel switches (other than brake fluid low) function as normal.

Now, I do not recommend repairing the stop switch itself as it is an item designed to be replaced and not repaired. I really just wanted to see if it was indeed only the switch that was a problem. The next step is to replace the switch with a new one.

Onto bigger and fresher endeavors: fixing the AC.

Thanks y'all.
 
Last edited:
Joined
Jul 25, 2021
Messages
86
Location
Toronto, ON
Hi Op, where is the stop light switch part located? I too seem to be having the problem where my CC only works where I tip my brake pedal up.
 
Joined
Dec 10, 2007
Messages
9,127
Get down on the floor by the brake pedal, turn your head and look up and rearward a bit (it's hard on the neck). Then follow the brake pedal arm until you see a metal and blue plastic round thingy, that's the switch.

Looking up from the driver's footwell (photo is of a LHD FZJ80):

FZJ80 Brake pedal return spring brake switch and cushion.png
 
Last edited:
Joined
Dec 10, 2007
Messages
9,127
Two things to check are the brake pedal return spring (is it present, connected at both ends?) and the small black plastic cushion located between the "nose" of the switch and the brake pedal arm (magnify the photo above by clicking twice).
 

Users who are viewing this thread

Top Bottom