A common problem but a little bit different. . .
02-23-2015, 06:29 PM
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A common problem but a little bit different. . .
Hello,
I'm a new guy to first gen's and new to the forum - very guilty of lurking. Anyways, I've been having a problem with my truck that seams to be fairly common but slightly different than what other people have described. When I am stopped and have the brake peddle depressed my ABS light and Brake light illuminate - but unlike most people describe the both these lights go away as soon as I begin to accelerate. Example of this would be, sitting at a long stop light, the ABS and BRAKE light come on, light turns green I drive away and the lights go off. Also, similarly I am slowing down coming to a stop (holding the brake peddle down) the lights will appear AND i will temporarily lose power steering. This is obviously very annoying when attempting to park! I figure this is a vacuum issue… maybe you guys can give me some advice? also, my cruise is out and has been out since I got the truck last July.
I'm a new guy to first gen's and new to the forum - very guilty of lurking. Anyways, I've been having a problem with my truck that seams to be fairly common but slightly different than what other people have described. When I am stopped and have the brake peddle depressed my ABS light and Brake light illuminate - but unlike most people describe the both these lights go away as soon as I begin to accelerate. Example of this would be, sitting at a long stop light, the ABS and BRAKE light come on, light turns green I drive away and the lights go off. Also, similarly I am slowing down coming to a stop (holding the brake peddle down) the lights will appear AND i will temporarily lose power steering. This is obviously very annoying when attempting to park! I figure this is a vacuum issue… maybe you guys can give me some advice? also, my cruise is out and has been out since I got the truck last July.
02-23-2015, 06:42 PM
#2
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Mine did that once. Turned out to be a blown fuse. I don't remember witch one it was though, it was a long time ago and it only did it once.
And
And
02-23-2015, 07:35 PM
#4
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02-23-2015, 10:15 PM
#6
Registered User
You haven't listed what you drive, but I'm guessing it's an automatic transmission.
What happens when you stop is the engine speed slows down. If the vacuum system has a weakness, either in the pump or a small leak, the vacuum pressure goes down. When you speed up, the pump then pulls enough vacuum to overcome the problem.
There's a switch on the frame, drivers side with a vacuum hose and a wire going to it. Thats's the low vacuum switch. When vacuum is low, it lights both lamps. Disconnect that wire. If the lamps do not light, then you've found the problem. The vacuum switch is not bad, but you have a leak in the vacuum system somewhere. It could be the brake booster, or a leaking hose or connector in the heater controls, or a leak in the hoses under the hood. The vacuum pump may be getting weak also.
The best way is to check the pump with a vacuum gauge, then use the gauge to find the leak if the pump tests good.
What happens when you stop is the engine speed slows down. If the vacuum system has a weakness, either in the pump or a small leak, the vacuum pressure goes down. When you speed up, the pump then pulls enough vacuum to overcome the problem.
There's a switch on the frame, drivers side with a vacuum hose and a wire going to it. Thats's the low vacuum switch. When vacuum is low, it lights both lamps. Disconnect that wire. If the lamps do not light, then you've found the problem. The vacuum switch is not bad, but you have a leak in the vacuum system somewhere. It could be the brake booster, or a leaking hose or connector in the heater controls, or a leak in the hoses under the hood. The vacuum pump may be getting weak also.
The best way is to check the pump with a vacuum gauge, then use the gauge to find the leak if the pump tests good.
02-25-2015, 02:04 PM
#7
Registered User
Seakid,
Both my rigs did this over all the years I've owned them. The "weak" brake boost problem is well documented on these rigs. It could be a worsening leak in the vacuum, but my 91 did it almost from new. It was worse in cold weather but was replicable anytime if I held my foot on the pedal while engine speed was slow. It's been a little nerve wracking at times such as when I had to back down Jeep trails with a cliff edge on one side, but I just kept my foot in it and adjusted to a "manual" brake feel. I never put a gauge on either rig, so it may have been a "fixable" leak or booster repair, but it never got worse over many thousands of miles.
Both my rigs did this over all the years I've owned them. The "weak" brake boost problem is well documented on these rigs. It could be a worsening leak in the vacuum, but my 91 did it almost from new. It was worse in cold weather but was replicable anytime if I held my foot on the pedal while engine speed was slow. It's been a little nerve wracking at times such as when I had to back down Jeep trails with a cliff edge on one side, but I just kept my foot in it and adjusted to a "manual" brake feel. I never put a gauge on either rig, so it may have been a "fixable" leak or booster repair, but it never got worse over many thousands of miles.
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