Been searching the site for info on thos without sucess. Bought a 98 ltd 4x4. The ABS light was on when purchased. It appears that the rear brakes are not working at all. I have a gravel driveway and when backing up and applying brakes, the front tires lock up. Not sure how to begin with diagnosis.

 

The brake system has a built in bias to the front brakes. A very considerable bias. During braking on pavement, weight transfers forward and the rear axle unweights, as a result the front brakes generlly do the vast majority of the work. It's not surprising at all that with ABS not working, the fronts lock up first when going backward.

Here's how to read a code off the ABS system, that will point you toward a cause:
Often it's the front wheel sensors - they're magnetic and can accumulate a covering of must and metal bits from the brake rotors. Eventually they have so much crud stuck on them that they no longer sense the teeth on the sensor ring. If that's the case you just need to remove the rusty stuff that's sticking to the sensor and it will start working again.

 

Thanks..I will try this out and report my findings.

 

used a paper clip to jump the E1 and Tc terminals as described in the video. when I turned on the ignition, the abs light did not blink at all. I did notice some other blinking. the air bag light and the cruise control light with blinking. went to the vehix411 site to try and get info for this and was not successful. any ideas?

 

Found another post on this site that described the process for getting the abs codes. It mentioned a step not mentioned in the video. In the diagnose box there is a removable shorting pin that needs to be removed first. After removing this pin I received a 32 code.

 

As for the built in bias you mentioned, I am currious if there is a proportion valve or some other way to adjust thos bias? I honestly don't think my rear brakes are functioning at all. When I have some help here I plan to remove the drum and see if there's any movement.

 

Maybe they just need adjusted? The rear brakes on these rigs dont really do much other than help stabilize the rig under heavy braking conditions... I have only front brakes in my rig atm, and I hardly notice the difference UNTIL I hit ice.... then the rear wheels will continue to push me along with the fronts locked

Oh... and the abs light could also be linked to a bad wheel bearing.... I have seen them cause numerous abs codes....

 

Thanks for the info..I will try these ideas out.

 

Wouldn't the rear brakes be more likely to lock up on the gravel if the truck were traveling forwards?

 

After diagnosing the abs code 32 I removed the sensor at each wheel to inspect and clean. Front wheel sensors didn't appear to be too dirty but wiped them clean and reattached. The rear sensors both had what appeared to be gear oil on them. (Thinking that is not supppsed to be there) wiped them and reattached. Drove the vehicle afterwards for a 4 mile drive and achieved 60 mph and as of now the abs light has not reset/off. As for the rear brakes, I removed the drums and had my wife press the brake pedal (engine running) as I inspected. What I noticed is this..the slave cylinder only seemed to be pushing the trailing side (toward the rear) on both sides. I'm uncertain of the slave cylinder is supposed to push both sides, but seems to me it should. I'm curious to know if this is a malfunctioning part or not. Could it be air in line issue? I suppose I will drive the vehicle a while longer to see if the ecu for the abs system will cycle and clear.

 

After more research I have found a procedue to clear the abs light but didn't have sucess. This is the procedure I followed. Used a paper clip to jump the tc and e1 and removed the short pin. Turned on the ignition and pumped the brake pedal several times (as many times as I could before the chime quit)
The abs still keeps flashing the 32 and 31 code which I believe is the sensors left and right front.
Is there any additional steps I have missed to clear the code?

 

the front-rear brake bias is built into the abs actuator and abs computer unless your truck is equipped with both abs and lspv. however, the adjustment of the lspv can be up to a certain bias only. the fronts still do most of the braking to prevent the from rear skidding sideways during heavy braking.

you might like to check the alternator because a certain fault in the alternator causes the abs light to lit up. toyota designed it that way.

 

Bizarre about the alt causing an abs light..I will check it. Earlier in the thread I refered to the rear brakes "slave cylinder" as I didn't realize the correct term is wheel cylinder. I inspected the fuctionality of this part and it doesn't seem to be working properly. It has a pair of pushing pistons to operate the leading and trailing brake shoe but it only seems to be pushing the trailing. I will purchase new wheel cylinders and see if that works. As for the abs system and the abs light, if the alt doesn't seem to be the problem, I will try to replace the sensors. Also mentioned earlier that when I pulled the rear sensors they had gear lube on them. I believe this indicates failed axle seals. Parts seem cheap enough but the repair might be outside my driveway mechanic experience.