DIY: ABS running frequently? How to do a 15 min partial ABS Flush

[cakes]

The First Generation Honda ALB system is the Achilles heel of the G1 legend. Most ABS problems come from the fluid sitting unused and unchanged for long periods of time. The cap on the reservoir doesn't form a perfect seal, so moisture and dirt will inevitably make it into the fluid and end up in the seals of the modulator. The solenoids in the modulator hold brake fluid at ~3000 psi, and when dirt is in the seals, the pump will run frequently, for a few seconds, building the pressure back up. Engaging the ABS will move the fluid so the solenoids will seal again, but the pump will end up running again shortly.

To solve this, you can do a complete flush, which involves removing the battery and airbox, getting the special honda tool, and carefully make sure you don't get hurt using releasing the high pressure fluid.

Alternatively you can do a partial flush, which takes 15 minutes.
Note I: I did this same procedure 1 month ago and it was very dirty, so when I did it again and took these pictures, my fluid wasn't nearly as dark and didn't have many dirt particles in it.
Note II: This same procedure probably applies to the G2, but you'd need to verify wire colors, motor relay location, ect...
Note III: Follow this procedure at your own risk, I nor acuralegend.org are responsible if something happens to you or your vehicle.

Supplies:
syringe, DOT3 brake fluid, q-tips, jumper wires with alligator clips or clip ends

1) Remove fluid from the ABS fluid reservoir with the syringe

2) Remove the filter and clean it with q-tips and shop towels - there will probably be dirt in the screen and on the bottom

3) Clean the inside of the reservoir with q-tips - especially pay close attention to the ridges of the container and the areas around the screws holding it to the modulator. When you're done, add fluid back in so the in/out areas are completely immersed in fluid.

4) These are the connectors for the 3 ABS solenoids that you're about to click. Make sure to note their location and what they connect to:

5) Using the wires connect the following to the battery - Black Wire - Ground, Red Wire - Positive, you don't do anything with the yellow wire. Click it back and forth several times for each of the 3 solenoids

6) Locate the ABS Motor relay in the fuse box and identify these 2 terminals. Connecting these 2 with a jumper will make the motor run.

7) Run the ABS motor to build pressure back up and run some fluid through the system. DO NOT run for more than a few seconds - the pressure could get too high!

8) Go back and forth between clicking the solenoids and powering the motor. If the fluid in the reservoir becomes dark again, suck some out with the syringe and pick up the dirt with qtips and repeat.
9) When you're all set, put the filter back in, top off the fluid, reconnect all the solenoid connectors, and put the motor relay back in the fuse box. This is fluid that's left over (I'm pretty sure this container has seen other fluids)

10) Drive the car to make sure the ABS pump doesn't run again and cycle fluid through the system in a parking lot or area with loose ground - wet leaves works best.

[l4zy415]

Great right up Waseem. This will help out every one that has ABS system.

[jerzylgnd]

May have to try this. ABS sometimes has a fit and runs a few seconds each drive for about a month, then goes away.

[PSA]

Guess I should offer an alternative. Take off cap, suction out crud. Remove 2 screws holding reservoir on and carefully remove it . Carefully being the operative word here so you don't damage the o-ring seal. Clean it with brakeclean and reinstall when it's dry. Refill. Get a 3ft extension, ratchet, and a 5/16 square drive socket. This will reach all the way to the bleeder on the accumulator (see service manual ). Open bleeder leaving socket and extension firmly on top of it. All the foam and crud will escape and make a mess so have a garden hose ready to wash everything off down there. To get the abs motor to run you need to jack up one wheel with the engine running and spin it. (you can just put it in gear for a moment as long as you have the ftr up and not the rear). You may need to bleed the accumulator several times before you get clear brake fluid and not just foam.

[paulo57509]

Because I used to flush the ALB system quite often (before the Modulator started leaking internally), I made this box:



One switch turns the pump on (you can run it for 30 seconds max without worries); the other switch operates the solenoids.

I even invested in the Honda bleeder wrench as well.

[PSA]

Sorry, forgot you folks also need to exercise the solenoids. Use both methods to completely clean out the system. Mea culpa, I've been spoiled because I have a Honda ABS checker.

[cakes]

Paulo57509 - that's a great setup you've got there

[3GCVC]

Just a quick tip for cleaning the ALB reservoir, you can drain the brake fluid completely with the syringe, remove the two screws at the bottom of the reservoir and remove the whole reservoir tank to clean out all the debris with it off the car.

PS to keep your braking and ALB system in good shape you should change the brake fluid every two years. If you don't there is a buildup of old brake fluid that takes a long time to get out(by changing the fluid) I have changed mine on the KA3 about 4 times now as its condition kept deteriorating within a month, then every couple of months.

[AcuraLegend55k1990]

Thanks guys this has been helpful now I just need to know how to change my pads and bleed the air out of my brake lines

[Honda600King]

Thanks for the helpful write-up!
If you don't want to fuss with the wiring, here's a method I have had great success with:

I first had this problem with my '92 NSX. The pump would run for about 90 seconds then shut down - ASB warning light on - until the next start-up. The dealer said the car needed a new ABS modulator that would run about $6K. On my own I removed and replaced the fluid from the reservoir and went out and "exercised" the ABS. That did the trick. I did it 2 or 3 more times for good measure. Fixed!

My '88 Legend's pump would come on and off constantly while driving. It was pretty embarrassing. The dealer said there was an internal leak in the pump and it would have to be replaced. I checked and the ABS fluid was pretty much black and the bottom of the screen had a fine silt. Believe it or not just cleaning the screen as described in this post helped a bit. I exchanged the fluid again like before and "exercised" the system about 6 times - the problem was solved! After each drive and motivating the ABS system on a gravel-covered road the fluid would be dark again. However each time it was lighter than before.

It's easy, cheap and makes you feel great that you resolved a problem the mechanic said would cost thousands to fix! It's essential for all our older cars that fluids be replaced and in the case of power steering and ATF, that Genuine Honda/Acura fluids be used.