ABS light constantly on, no idea if it even works - can I still bleed the brakes? (1 Viewer)

[math]

Our ABS light has been on since the day we bought the truck, previous owner did 7-pin mod. I've got no idea why it's on and no idea if ABS actually works. Frankly, I'm hoping the sensor is just not plugged in or something, which I should see during the front axle teardown.

Should I go out and do some panic stops and see if I can tell if it's on? Can I still bleed the brakes when I do my front axle rebuild? I was going to disconnect the calipers and shine them up a bit, no rebuild, plus the brake fluid is nasty. I'm told I should activate ABS but that would involve diagnosing the system, which is likely beyond my abilities. A ludicrous amount of my driving is off road anyway, so I'm not too worried about not having ABS.

Thanks.

 

[arcteryx]

Any codes?

 

[math]

Any codes?

No, but I don't have an ABS code reader - just a Scangauge II, which I (possibly erroneously) assume won't give me those codes. Am I correct?

 

[arcteryx]

I'm not a OBD2 guru but would think that a code would show up if the light is on. i would check that all your sensors are plugged in securely and then get out the FSM and follow the diagnostics. I am thinking you have a bad sensor but you don't want to just start throwing money at parts unless you can figure it out. my 2 cents

 

[math]

I'm not a OBD2 guru but would think that a code would show up if the light is on. i would check that all your sensors are plugged in securely and then get out the FSM and follow the diagnostics. I am thinking you have a bad sensor but you don't want to just start throwing money at parts unless you can figure it out. my 2 cents

I'm okay with ABS not working, I just don't know if I can bleed the brakes if it isn't. Apologies. Still okay to just flush the fluid?

 

[arcteryx]

I'm okay with ABS not working, I just don't know if I can bleed the brakes if it isn't. Apologies. Still okay to just flush the fluid?

definitely, its not a direct correlation. there are many cruisers (heck cars for that matter) pre 93 that dont have ABS. you are mixing electrical bits with mechanicals. bleeding the brakes are mechanical on these not like the later models where it gets complicated. finish up and go for it.

 

[Fj moneypit]

My abs wire on my 4Runner got stretched when putting on lift and made light go off. Checked wires, pushed on ends where it plugs in and light went off. I'm assuming land cruiser is same. Check sensor wires where they plug in at brake.

 

[Dave 2000]

The normal mode is the ABS light goes out at start up assuming all connections at the ECU, the sensors (including the one under the centre console) are good. If the light comes on as the wheels start to rotate then this will bring up the light if a wheel slip sensor is not working correctly. Yes you can go ahead and bleed the brakes but, sometimes the pedal lacks 'bite' due to trapped air, and some activation of the ABS allows air trapped under the valves to escape. Heard many times that activating the ABS can help pedal feel, it did for mine recently despite pressure bleeding.

regards

Dave

 

[math]

If the light comes on as the wheels start to rotate then this will bring up the light if a wheel slip sensor is not working correctly.

This is exactly what happens - takes about five to ten feet of travel before it pops on. Where are the sensors? Thanks!

 

[Dave 2000]

The sensors are bolted into the hubs behind the brake discs. You should remove them carefully and clean and check for damage, you can use an ohm meter on the connector plug, look for the resistance changing as you rotate the hub. Some of the things I have seen:

The wrong CV joint having been fitted with NO tone ring.
The tone ring having teeth missing.
The tone ring having left the CV joint, but the noise would drive you nuts.
Bits of metal stuck to the sensor magnet.
Physical damage cause by removal or replacement.
Broken wires, dirty connections.

Be warned they are quite expensive, hence the reason some people do not replace them, it is part of the test here to see the light goes out, but they do not check if it comes on as you move through the test bay through the various test areas.

regards

Dave

 

[math]

@Dave 2000

Bearing that in mind, we should rebuild the axle and THEN bleed the brakes, right? I understand it now. Deeply appreciated. I'd like ABS to work but it's not a huge deal when 90% of my travel is on dirt.

 

[IronCladLou]

This is exactly what happens - takes about five to ten feet of travel before it pops on. Where are the sensors? Thanks!

My ABS light comes on at exactly 14 mph. I broke the sensor in the passenger's side front hub when doing my axle service and never fixed it. Brake bleeding is not affected and neither is braking in general - you just won't have ABS...

 

[TrickyT]

The OBD-II diagnostic port is not connected to the ABS ECU in an 80-series. So you cannot read ABS diagnostic codes with a ScanGauge. But there is a procedure described in the repair manual for reading ABS ECU codes based on how many times the ABS dash light flashes when placed in diagnostic mode. (3FE owners must use a similar procedure when reading engine ECU codes.) Here are the relevant pages from the FSM that shows you how to do this:

 

[SmokingRocks]

Guaranteed speed sensor. Mine was the same. Delete the abs system, bypass he lspv and remove the abs bulb from the cluster. You will be much happier.

Also those speed sensors are stupid expensive