ABS module bleed suggestions????
1998 p30 chassis, 4 wheel disc with hydraulic brake boost from the power steering pump. Replaced the master cylinder with a bench bleed. Replaced the hydraulic booster. Replaced all 4 brake calipers....
Forum Discussion
Update!!!!!
I jacked up the rear of my 98 chevy P30 chassis, put jackstands under the rear axle..... easy peasy with the new 12 ton hydraulic bottle jack that the wife picked up for me at HF. 3 ton jack stands.
Ran it up to 55 mph, gave both rears wheels time to get to an even speed, then slammed on the brake as hard as I could.... did this 3 times, then shut it down and brake pedal bled all calipers with the engine off. Nothing new came out of the rear calipers. BUT... GOT SOME AIR BUBBLES FROM THE FRONT RIGHT CALIPER. So, I did it again and got some more air bubbles from the front right caliper...... Third time, no bubbles....
Pedal firmed right up, still just a bit more of a drop to the braking point than I would like, 1 to 1.5 inches, but the pedal doesn't drop, feels squishy or pump up. Poor wifes legs were jelly after pumping the pedal for hour!!! But couldn't have done it without her... and that hydraulic bottle jack... what a cool new tool!!
So, drove it up the dirt road across the street, pulled into the sand on the shoulder and slammed on the brakes.... I could feel the front wheels releasing and braking, yeah!!!! did this several times then tested on the pavement. It squats just like is did when it was new!!! Yes, I've had it that long... bad news, the power steer pump is wet on the bottom.... rebuild kit here I come...
Lastly, my GM tech2 scan tool, refuses to link up with the ABS module. I checked it on my 96 eldo and it reads it perfectly. It connects with the 7.4L moho engine perfectly. First I went through and pulled all the connectors to check for bent or dirty pins, then cleaned the grounds. No change, no link. When I checked on line other folks were having problems getting their GM tech2 tools to link with Kelsey Hayes 12765501 ABS brake module. So, apparently there is some sort of glitch in the module that prevents it from linking up. These units were used in chevy trucks and P30's 1997 to 1999.
The "slam the brakes" method is the only way to bleed these suckers...
Thanks for the offer of the wiring schematics. I have a complete chevy shop manual for this moho. It says it should connect, wiring schematic says it should connect.... but doesn't.. why??? I can't say....
Thanks everyone for your help!!
I jacked up the rear of my 98 chevy P30 chassis, put jackstands under the rear axle..... easy peasy with the new 12 ton hydraulic bottle jack that the wife picked up for me at HF. 3 ton jack stands.
Ran it up to 55 mph, gave both rears wheels time to get to an even speed, then slammed on the brake as hard as I could.... did this 3 times, then shut it down and brake pedal bled all calipers with the engine off. Nothing new came out of the rear calipers. BUT... GOT SOME AIR BUBBLES FROM THE FRONT RIGHT CALIPER. So, I did it again and got some more air bubbles from the front right caliper...... Third time, no bubbles....
Pedal firmed right up, still just a bit more of a drop to the braking point than I would like, 1 to 1.5 inches, but the pedal doesn't drop, feels squishy or pump up. Poor wifes legs were jelly after pumping the pedal for hour!!! But couldn't have done it without her... and that hydraulic bottle jack... what a cool new tool!!
So, drove it up the dirt road across the street, pulled into the sand on the shoulder and slammed on the brakes.... I could feel the front wheels releasing and braking, yeah!!!! did this several times then tested on the pavement. It squats just like is did when it was new!!! Yes, I've had it that long... bad news, the power steer pump is wet on the bottom.... rebuild kit here I come...
Lastly, my GM tech2 scan tool, refuses to link up with the ABS module. I checked it on my 96 eldo and it reads it perfectly. It connects with the 7.4L moho engine perfectly. First I went through and pulled all the connectors to check for bent or dirty pins, then cleaned the grounds. No change, no link. When I checked on line other folks were having problems getting their GM tech2 tools to link with Kelsey Hayes 12765501 ABS brake module. So, apparently there is some sort of glitch in the module that prevents it from linking up. These units were used in chevy trucks and P30's 1997 to 1999.
The "slam the brakes" method is the only way to bleed these suckers...
Thanks for the offer of the wiring schematics. I have a complete chevy shop manual for this moho. It says it should connect, wiring schematic says it should connect.... but doesn't.. why??? I can't say....
Thanks everyone for your help!!
