The Diesel Garage banner
1 - 10 of 10 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
Hello, I just purchased a 98 4700 with 466e motor and a 6+1 trans. It has juice brakes and the brake pressure light comes on after 20 min. of operation. If I turn the truck off and on again. It goes out then comes on shortly thereafter. I don't notice any difference in brakes, they seem good. Truck has 111k on it and I just don't know enough yet to know where to start looking. Any help would be appreciated. Thanks in advance. John
 

·
Senior Member
Joined
·
3,754 Posts
You need to start checking pressures. We had a few trucks w/intermittent brake prssure lites. We never fixed them and never lost brakes but dont like having drivers tell ou that tthe light comes on. Boss says as long as you still got brakes dont worry about it . It only takes one time they dont work to make a heck of a mess.
 

·
Registered
Joined
·
44 Posts
I had the same problem with my truck. If you go here. http://www.bscparts.com/pdfs/hydromax.pdf and you'll see in the first pic [integral flow switch]. I just had to replace the switch and it stopped. I cant guarantee it but it worked for me. Its a very cheap part at the I.H. store and they should have it in stock. I have also seen the ignition switches cause problems to. They get hot at the back of the switch and it melts the big connector that plugs into the back. Just remove the switch and inspect the back of it.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #4 ·
Thanks for the tips!

Thanks, I will try this tomorrow and see if we can fix it. I noticed that the fluid is about 1" below the cap ring. Isn't it supposed to be up to the ring? I will try fluid first and then check the other items you mentioned. Thanks again. This forum is a great resource. John
 

·
Fire App. Mech.
Joined
·
982 Posts
The fluid will always drop as the pads wear but as long as there is a good amount in there it will perform the same. You should never have to add any during normal use, that indicates a leak. I flush them out with new fluid from time to time and always fill to the top after a brake job (I buy loaded calipers so I lose the fluid that is in the old ones).

Birken
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #6 ·
98 4700 brake pressure light

Well we changed the sensor, all the fluid is up and went to back out of the shop and the light and buzzer came on. Shut truck off for 5 min. started and no buzzer or light. Drove 15 miles and no buzzer or light. Went to back up and you guessed it, buzzer and light on. It seems to only be coming on when I back up. Does anyone know if it could be due to the fact that it is a cab/chassis that only has the brake lights and turn signals hooked up, that could cause it to trip somehow? I can't think of any other reason for it to happen. It only comes on in reverse. :shrug:
 

·
Senior Member
Joined
·
455 Posts
a good cause for that light to come on for no apparent reason can be from brake switch issues the brake switch is a 2 part switch it recieves power from two sources and sends power out from each side of it .

check to see if both sides of the switch have 12 volts to them with no brake applied then check that both outputs get 12 v with brake applied if that checks out ok then another possiblity is back feed of power thru tail light or even reverse light circuits verify the tail lights have a good solid ground to them and that the lights are properly wired in
 

·
Super Moderator
Joined
·
4,247 Posts
Bad grounds in the brake/tail/back-up lights WILL cause the Brake Warning light and buzzer to activate for no apparent reason.

Reason: The brake circuit does not have a blocking diode in it to prevent "backfeeding" of electricity due to an open or partial ground circuit in the rear lighting circuits.

Cause: Loss of good ground allows electricity to "back feed" from another circuit sharing the same ground as the BRAKE lights, into the Brake Warning Module. The module detects ONE brake signal, but not two, and illuminates the warning light and sounds the alarm. The module is designed to do this as there are two seperate brake switches, and it thinks one has failed.

This is VERY common.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #9 ·
98 4700 brake pressure light

Thanks to all that gave feedback, I did get my flatbed installed and wired and you were right. The warning light and buzzer do not come on at all. Simple fix, and a little more knowledge gained. Thanks again. John :thanks:
 

·
Registered
Joined
·
1 Posts
Hello, I just purchased a 98 4700 with 466e motor and a 6+1 trans. It has juice brakes and the brake pressure light comes on after 20 min. of operation. If I turn the truck off and on again. It goes out then comes on shortly thereafter. I don't notice any difference in brakes, they seem good. Truck has 111k on it and I just don't know enough yet to know where to start looking. Any help would be appreciated. Thanks in advance. John
Hello, I just purchased a 98 4700 with 466e motor and a 6+1 trans. It has juice brakes and the brake pressure light comes on after 20 min. of operation. If I turn the truck off and on again. It goes out then comes on shortly thereafter. I don't notice any difference in brakes, they seem good. Truck has 111k on it and I just don't know enough yet to know where to start looking. Any help would be appreciated. Thanks in advance. John
You need to start checking pressures. We had a few trucks w/intermittent brake prssure lites. We never fixed them and never lost brakes but dont like having drivers tell ou that tthe light comes on. Boss says as long as you still got brakes dont worry about it . It only takes one time they dont work to make a heck of a mess.

You can do that (just ignore it) however when it fails its bad. We had a 1998 GMC top kick rollback. We thought everything was good on it, it even passed DOT inspection and state trooper inspection with flying colors. 1 week later my son was driving it with 2 cars loaded on it. Girl stopped in front of him, truck locked up welded the front brakes together, he missed the girl in front of him went off the side of the road and traveled over 500 yards, hit 4 parked cars, 2 brick pillars, jumped a 5 ft deep culvert, and stopped just before he went through the front of a building. Lost both cars off of it, the one on the deck almost went through the back of the cab!! Come to find out the back brakes were rusted and weren't working but you couldn't tell it without removing the back tires. End story? Check out whatever you buy used throughly or your liable to be damn sorry you didnt.
 
1 - 10 of 10 Posts
Top