Bleeding brakes and needing the ABS scanner tool procedure?

[rotohead]

In the FSM there is a section about brake bleeding and the need to run a DRBIII scan tool program to purge air from the ABS. Replacing calipers and BMC and wondering if this is really necessary? Anyone?

 

[Bob4x4]

It should be done when replacing any components in front of the abs module.Bench bleed the master before installing it.You should bleed the base brakes first.You can get the job done by repeated panic stops,hard enough to activate the abs but it is not the safest way.After doing that you will need to bleed the base system again

 

[rotohead]

Thanks for that info very much. Do you know the criteria needed to activate the ABS? There is a very large empty asphalt lot near me I could try to make a series of hard stops. The dealer wants $100 to run that ABS scanner tool routine. It's BS you need the dealer or someone with a expensive scan tool to properly bleed brakes.

 

[JR]

Gravel roads work better, the wheels need to skid to activate the abs. Once you feel the pump cycle a few times you'll need to go thru and re bleed the wheels and repeat until the pedal is satisfactory. How many times that requires depends on how much air you introduce into the abs, if you keep the brake lines above full and properly bench bleed the master it shouldn't be bad. On the other hand if you open the lines up at the calipers and let the lines drain overnight your gonna have a real time of it...
100 bucks is probably about par, figure a minimum of an hour's labor plus supplies. Gotta make money to keep the lights on.

 

[rotohead]

Gravel roads work better, the wheels need to skid to activate the abs. Once you feel the pump cycle a few times you'll need to go thru and re bleed the wheels and repeat until the pedal is satisfactory. How many times that requires depends on how much air you introduce into the abs, if you keep the brake lines above full and properly bench bleed the master it shouldn't be bad. On the other hand if you open the lines up at the calipers and let the lines drain overnight your gonna have a real time of it...
100 bucks is probably about par, figure a minimum of an hour's labor plus supplies. Gotta make money to keep the lights on.

Thanks. The asphalt lot I was referring to is a ski resort and it's always slick. I could go up there after hours and it's big enough to get the tires to skid. Then bring my Motive pressure bled system with me and bleed the system completely right there in the lot. I thought there was a minimum speed to go before ABS was active.

 

[rotohead]

Also, does anybody know if the button on top of the combination valve is a 'bleed' valve? You can see it when you remove the little mushroom rubber cap on top of the combination/differential device next to the ABS module?

 

[rotohead]

Yep, you can bleed air from in front of a ABS module without the need for a scan tool. It takes multiple triggering of the HCU and solenoids to get it done. I probably did 10-12 hard stops on a abandon road in the mts that was a sheet of ice. I would bleed using a Motive pressure system about every third stop and I could see some air (not much) feel slight improvement in the pedal feel until the last few stops. Then it felt as normal as it's ever felt.