Abs Diagnosing

[DaSovietPotato]

As long as I have had my Ex I have noticed that the ABS sometimes activates after the transmission downshifts before coming to a stop. At some point I am hoping to take a look at the ABS system and fix the problem. Last summer I would have the occasional ABS light when starting, however I have not seen the light since then. I was wondering where I should start on the ABS system. For the time being I have taken out the ABS fuse, and I don't expect snow in July. This might not be an extremely large issue, however I would simply like to get the preventative maintenance in order before I have to crawl under in 0 degree weather.

 

[ChildIdenticant]

First, No reason to pull the fuse as the abs failing will return the brake system to normal braking for your system (teves mark iv (g)) btw.
....did your ABS actually work even though the error lamp was lighting up? I have never read anything on this forum about an intermittant ABS lamp, Something normally fails outright, as I have read.

 

[Fix4Dirt]

As long as I have had my Ex I have noticed that the ABS sometimes activates after the transmission downshifts before coming to a stop. At some point I am hoping to take a look at the ABS system and fix the problem. Last summer I would have the occasional ABS light when starting, however I have not seen the light since then. I was wondering where I should start on the ABS system. For the time being I have taken out the ABS fuse, and I don't expect snow in July. This might not be an extremely large issue, however I would simply like to get the preventative maintenance in order before I have to crawl under in 0 degree weather.

can you check/clean the aheel speed sensors?

 

[DaSovietPotato]

I have had no light since last summer, however I unplugged the fuse because the system is still operational despite the problem I am experiencing. I am thinking that I might test the output of the sensors before I get it up on jacks and remove the wheels.

 

[Fix4Dirt]

I have had no light since last summer, however I unplugged the fuse because the system is still operational despite the problem I am experiencing. I am thinking that I might test the output of the sensors before I get it up on jacks and remove the wheels.

that would be a good approach

 

[CDW6212R]

First flush out all of the brake fluid. Dirty fluid contributes to all kinds of brake issues, it can't be clean enough. Be sure the fluid is clean and there have been no leaks. Making the ABS function every once in a while is also good maintenance, just mash the brakes once a month at a moderate speed for a couple of seconds. When the ABS engages, the internal valves open briefly and allows some fluid to pass through those. You don't want any old or dirty fluid to accumulate inside the ABS module, that can cause malfunctioning.

So keep the fluid clean if at all possible. Start with the fluid, it's way more important than the ABS sensors. The brake will work fine with an error code or bad sensors. Hopefully it's just the fluid, which is easy to fix. Testing and replacing the sensors can take a lot more time and money.

 

[J_C]

If 4WD, how old are your front hubs? Hubs wearing out can cause a front sensor to fail (or really I mean fail to send a signal but not necesssary sensor itself has anything wrong with it except possibly contaminated grease on it). They produce a low voltage AC signal to the ABS controller while the wheel is spinning, and measure a few hundred ohms (unplugged, at the sensor connector) - factory on my '98 was 420 ohms. When the ABS light is on is a good time to measure for that few hundred ohms at the ABS controller.

If the sensor is in a hub, it may be seized in by rust and break upon attempting to remove it. Check the wire to it for damage as well.

Don't forget that there's bound to be other forum topics about troubleshooting ABS.

I don't think some posters are realizing the potential fault here as I understood it, which is slowing to a stop, ABS activates and this prevents the vehicle from having full braking, and may also cause the vehicle to pull to the side if it's the front wheel sensor. It's also possible that this happens during braking at higher speeds (but the vehicle has not been subject to this) and that can be a safety issue, particularly on slick roads.

 

[DaSovietPotato]

I don't think it has anything to do with the hubs or the brake fluid since I had them completely disassembled/bled about a year ago when I did the last brake job. I also had the issue before I completed the brake job and it has not changed since. I think the problem might be with one of the ABS sensors, and I will probably start with that.

 

[J_C]

^ ?? you had the hubs completely disassembled? Do you have RWD or 4WD?

 

[RangerX]

Maybe try check for abs codes?