ABS light ON

[matuva]

It did happen today, after I had to brake a bit stronger than usual.

The ABS light came ON.

After I shut OFF the engine and restart, it was Off, but then re appeared as soon as I reach about 15 kph, then stays On, till I shut off engine, and so, and so...

I scanned the truck, no current code, after restart, or with this light On.

First time I scan, after a restart, I had no current codes, and following ones in history:
16 - vehicuke speed sensor buffer fault
56 - injection pump calibration resistor error (I get a brand new #9!)
78 - wastegate solenoid fault
84 - accelerator pedal position circuit fault

I cleared all, so no current codes and none in history.

Drove the Blazer, ABS light lite On as soon as I reach 15 kph. Let the engine iddle, light On, and rescan:
- no current code
found in history:
16 - vehicuke speed sensor buffer fault


Any thought? :skep:

Other than having this stupid light On, the brakes do work perfect, smooth and strong, no vibrations.

What may cause that?

 

[schiker]

What scanner are you using? I think it takes more than the avg code reader for ABS codes.

 

[ak diesel driver]

more than likely you have a bad speed sensor wire on one of the front wheels. also check out the wheel bearings as a bearing starting to go will mess up the speed sensor

 

[Turbine Doc]

more than likely you have a bad speed sensor wire on one of the front wheels. also check out the wheel bearings as a bearing starting to go will mess up the speed sensor

X2 when my bearing was starting to go up front just before the stub axle snapped I got a ABS lite, as the bearing powder as it disintegrated "fuzzed up" the ABS sensor

 

[matuva]

Could be wire or sensor itself I bet. On my 94 Blazer, the wheel reluctor is outside the hub, not like the late 95 and + which have the hub design changed and get the reluctor inside the hub

 

[gnel]

I had the same problem after a complete rebuilding of the front end. Black tape fixed it.

 

[matuva]

I had the same problem after a complete rebuilding of the front end. Black tape fixed it.

:???:

 

[gnel]

A little square of black tape stuck over that annoying dash lite.

 

[matuva]

Using the paper clip trick (Thanks to JMJNet ) I found these ABS codes :
*Code 65 : open or shorted pump motor relay
*Code 67: open motor circuit or shorted BPMV output

I have none to very few knowledge in ABS systems. Anybody knows what these code means? What motor are they talking about?

 

[schiker]

I don't know much either but isn't that the ABS unit on the fenderwell (at least its on drivers fender well of my 97)? The pump is what modulates the pressure for antilock pressure or maybe it relieves the pressure from the master cylinder dunno. Never confirmed this but heard the unit is pricey. I don't know if its servicable. Sometimes see complete used units on ebay. There may be different units OBDI vs II ??????

 

[Heartbeat Hauler]

There is also a ground for the ABS unit right underneath the driver's seat under the truck on a cross brace of the frame. Take off the ground wire clean the frame,ground wire end, and teh nut. Check the connection to the ABS unit under the truck inside frame rail. Check wires running from the wheel sensor up around the control arm. That's usually where it rus the insulation off and then shorts out the speed sensor.

Then Jsck up your truck in teh front, grab the tire at the 12:00 and 6:00 position and give it hell back and forth, if you get any movement the wheel hub is on it's way out. I hope it's something simple, mine was the ABS unit $2200 parts and labor!!!....at:

 

[millsroger]

View attachment Rear Wheel Antilock Brake codes.docI found this list of ABS codes and how to retrieve and clear them for the RWABS

 

[Big T]

There is also a ground for the ABS unit right underneath the driver's seat under the truck on a cross brace of the frame. Take off the ground wire clean the frame,ground wire end, and teh nut. Check the connection to the ABS unit under the truck inside frame rail. Check wires running from the wheel sensor up around the control arm. That's usually where it rus the insulation off and then shorts out the speed sensor.

Control arm? Is this on the passenger side sensor? From the plug to the ABS unit? Should I trace it looking for frays or just test with an Ohm meter?

Last time I took it in I had a code indicating a short on the passenger side sensor. I replaced the sensor and the ABS light did not go away. Occasionally while offroading the ABS light will go off for a short while, but it inevitably comes back on.

 

[matuva]

May be the memory in the ABS puter needs to be cleared?

According to what I read, to do so you must:
key ON, no start
short pins A & H of the diagnostic plug for 2 seconds
release pins A & H for 1 second
short them again for 2 seconds and release
key off

It should be OK.