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Working on a 98 e250 handicap conversion van for a friend, she states that the ABS pump is running with the key off. I wasn't able to get the pump to run however when I test drove it the brake pedal travel was excessive. Let it sit about 20 minutes checked some things then drove it again the brake pedal travel was fine that time. She also stated that the ABS light came on the other night when driving and when that happened the brake pedal started going to the floor.
Could this be a faulty master cylinder losing pressure making the ABS pump kick on to make up the pressure loss? Faulty pressure switch?
Any help or advice would be much appreciated. Thank You
Faulty pressure switch won't make the pedal hit the floor. I take it you checked for leaks (has it been bled?) and the descending pedal isn't all the time. So that narrows it to master cylinder, brake booster, and possibly the ABS unit. ABS unit is the most expensive and I think will kick codes. Do a search on here for ABS and see if you get better info than me on that.
I have or had this same problem with my '03 E250---finally pulled the Maxi-Fuse in the Battery Junction Box or underhood fuse for the ABS pump. The electronic control module sitting on top of the pump block has failed---its upwards of $500 or more even for a cheap one.
Its doubtful there are any issues with the master cylinder---my '03 has logged almost 10K miles with the ABS light glowing in the instrument cluster, there is no loss of brake power. If that does exist its a separate issue but I'd pull the ABS fuse. In the case of the 1998 E-Series it will be #19 (60 amp) fuse found here:
Thank you i'll check that out. Was your pump running with the key off?
It was indeed---it would still run if I replaced the fuse right now. Since I'm about to dump that van it'll go unrepaired but could be driven another 50K miles without a brake problem.
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