Why Does My ALB System Keep Cycling?

[KJ, GM] Before visiting the dealer, find a deserted parking lot (preferably wet) and stomp on the brakes several times to activate the ABS system. A dirt or gravel road will also work if you don’t mind getting the car dirty.  This will sometimes free a sticky solenoid. It can also help flush out any particles which may be in the valve causing the fluid to slowly escape from the high pressure cylinder.  Regular use of the ABS, either on the road or in an empty parking lot, is recommended to help prevent the solenoids from getting stuck in place.

[,, RP] If that doesn’t fix it, get the system checked at the dealer. The three main causes of excessive ABS pump cycling are: a leak in the system; needing to have the system flushed; a bad ABS pump (needs replacing).

[A/H] My guess is that the ABS system was happy, but then when the modulator sprang in to action one of the valves in the modulator didn’t seat correctly after it did it’s thing when the wheel started to lock up. Usually by exercising the system monthly the valves will seat properly.

The ABS system has a pressure switch that turns on the pump when the pressure gets low. If one of the valves gets seated off center or if a small piece of matter gets in the valve, the high pressure leaks past the valve and then triggers the pump to pump up again. When you lock up the wheel with the valve that was leaking (leaking inside the system, not on the ground) the valve is given the chance to seat properly and thus the system is happy again.

This is not an everyday thing but it does happen.  If you have the problem again I would suggest finding a grassy area or sandy parking lot and do a couple of panic stops to make sure each of the 4 ABS system valves get a chance to be exercised.

[TC] I solved the problem last night by stomping *hard* on my brakes. It took ~20 minutes of hard braking before the ABS modulator unit was freed. I will probably still bleed and flush the ABS system on my next service.

This is just another example of how valuable the Internet and listserv groups are. Without the list or the NSX FAQ website, who knows, the local dealer may have ended up convincing me to replace the entire ABS system for $1800+.

By the way, for those that encounter this problem again, I found out there are 3 options the dealer offers:

  1. "Work" the system (basically they charge you $100 to stomp on the brakes)
  3. Bleed & flush the system ($75 - $150)
  5. Replace ABS system, modulator unit and all ($1800+)

When I asked the service rep what he meant by "exercise" the solenoid, he was very vague. After I grilled him a bit, he finally admitted that "exercise" means they take your car out and stomp on the brakes for you. I passed on all 3 options and tried stomping myself again. This time, after 10 or so tries, finally got the ABS system fixed. I also flushed both my brake and ABS system at my next service interval. If a dealer offers you the 1st option, obviously pass on it and do it yourself!

[VB] Local NSX mechanic: The ABS pump will run whenever the brake fluid in the accumulator drops below a certain psi. If the pump cannot restore pressure within 120 seconds the ABS computer puts the system in "fail safe mode" and lights the ABS ( ALB ) warning light. If the light comes on during start up ( as it should for "bulb check" mode) then stays off, the system is ok. However if the solenoids leak down, the pump will run more often.

Occasionally, after ABS engagement the solenoid will weep internally and the pump will cycle more. Sometimes the condition will correct it’s self, other times it takes operating the solenoids to get them to seal well again. One other symptom to watch for is if the pump cycles on and off very fast, say once every 5 minutes or so, and when the pump runs, if it only stays on for 1 to 5 seconds…. these symptoms indicate a depletion of nitrogen or a ruptured bladder inside the accumulator. The accumulator then fills completely with brake fluid and becomes " hydraulically locked."

ABS Doesn’t Kick In Right Away

[GM] At a recent track event I was able to briefly lock one of my brakes when braking from about 80mph. They seemed to lock for about 10 feet before the ABS kicked in. I later tested the ABS on a gravel road and it worked fine.

[RAR] I have noticed a similar effect at Laguna Seca going in to turn 5. For some reason, I seem to brake hardest for that turn. Definitely the brakes lock for a short time (10′? I have NO idea!) before the ABS kicks in. I subsequently tried this on the street in a safe little section near here and darned if they don’t lock briefly there, too.  My car is a ’94 with 40K miles on it. Always maintained by the local Acura dealer since new. No brake mods. The effect occurs with the OEM wheels and tires.