How to bleed the 91 abs system without the T wrench

Wavey1,
Sounds like your accumulator is dead. It is what "holds" the excess fluid under pressure until needed. If the diaphragm is bad or the air charge has leaked out, you need a new one. That is why the T-Handle tool is useful, it measures how much fluid the accumulator holds when fully charged.

find a good 2nd hand accumulator.

GraemeD said:

Wavey1,
Sounds like your accumulator is dead. It is what "holds" the excess fluid under pressure until needed. If the diaphragm is bad or the air charge has leaked out, you need a new one. That is why the T-Handle tool is useful, it measures how much fluid the accumulator holds when fully charged.

Click to expand...

Yes ^^

I have seen someone list a charging service for them. It was reasonably pricing, but I would just go new myself.

OK, looks like the next step is to check the accumulator. Best price on a new one is +/- $500. I'm leery of used for a part like this but I'll see what's out there. There is a guy recharging Audi and Saab accumulators and he now lists NSX too. But that's just a nitrogen recharge, not a rebuilding of the bulb or the diaphragm. https://sites.google.com/site/audicqturbo/audibomb

Looking at the cost of the test harnesses, T-bleeder, accumulator... and I'm seeing why so many recommend going with SOS's update kit and being done with it. Or eliminating the ABS with Pole2Flag's kit. Or disabling the system and leaving it in place.

BTW, Joe's test harnesses are top rate and a bargain at the price! I wish I could have grabbed one of the 4 T-bleeders that popped up recently - they get snapped up fast.

So, the diagnosis is my pump is functioning, my solenoids are functioning, but the system isn't building enough pressure because the accumulator is discharged, which is why I'm getting the weak result in the reservoir when I exercise the solenoids. Do I have this right?

Without the T-wrench and what you wrote so far, you can't tell whether you have pressure at the accumulator or not.
It is very unlikely for all 4 solenoids (in fact, there are 8 in total) to seize but making clicking noise doesn't mean they are operating fine.

Like you heard many times about the leaky ABS solenoid, these can fail in stuck closed mode and when this happens, even with the high pressure fluid stored in the accumulator, you won’t see any fluid returned to the reservoir when you hear the clicking sound after applying 12V at the Red and Black wires of the solenoids.

You should check the continuity of the ABS pressure switch.
If it’s On/Closed, you have achieved enough pressure inside the accumulator.
If it’s Off/Open, it is below the targeted pressure and thus, activates the ABS pump as soon as you exceeds about 5mph for the first time after starting the engine.
If the pump kept running for more than 2min, you would see the ABS warning light which was not the case for yours so seems like your ABS had enough pressure left inside the accumulator???

Again, check the pressure switch before getting replacement accumulator.

If you are thinking of servicing the ABS regularly, why not get hold of T-wrench especially if you are in US?


Kaz

Thanks very much Kaz! I will check for continuity art the pressure switch before I proceed.

I have been trying to buy a T-bleeder for months but they are NLA anywhere. I missed out on two listed here on Prime, and two that were on eBay, all sold before I even saw the ads.

So maybe my solenoids are NOT operating correctly. I'll hook up the harness again and try them more times than I have, see if they free up. When I activate them now, the fluid drops slightly then returns to normal level in a few seconds.

When I activate the ABS while driving, it does seem to be working - no brake lockup and I feel pulsating at the pedal, then the pump runs for a few seconds. ABS light has never been on.

I'm wondering if I just have low pressure in the accumulator, but not "no" pressure. Continuity test at the switch should help that diagnosis. The if I can ever find T-bleeder maybe I can figure out what the problem is.

The net cost from the guy that recharges the accumulator is $88.00 so that seems like it's worth a try before buying a new one. A new accumulator comes with the pressure switch too, don't see where the switch is available separately.

Thanks for everyone's help and I'll post the results.

Wellllll... get this. Just drove it for the first time since exercising the solenoids, and now the ABS light IS on, I do not hear the pump running, and the ABS is NOT working. All I did was to hook up the harness and exercise the solenoids, ran the pump a bit (never more than 15 seconds), pulled and replaced the ABS pump relay to hook up that switch, and checked the 3 ABS fuses. Everything went back together per original. WTF?!?

EDIT: Just checked the solenoid connectors again, they're good. Double-checked the two fuses, they're good. Pulled the relay and ran the pump with the switch, it's good. Everything is just like it was before I exercised the solenoids, but now the ABS ain't working. Grrrrr... On to checking the codes next, I guess.

What do I pull to get the ABS light to go out in the mean time? Heading out on a weekend trip in the AM.

Wavey1 said:

Wellllll... get this. Just drove it for the first time since exercising the solenoids, and now the ABS light IS on, I do not hear the pump running, and the ABS is NOT working. All I did was to hook up the harness and exercise the solenoids, ran the pump a bit (never more than 15 seconds), pulled and replaced the ABS pump relay to hook up that switch, and checked the 3 ABS fuses. Everything went back together per original. WTF?!?

EDIT: Just checked the solenoid connectors again, they're good. Double-checked the two fuses, they're good. Pulled the relay and ran the pump with the switch, it's good. Everything is just like it was before I exercised the solenoids, but now the ABS ain't working. Grrrrr... On to checking the codes next, I guess.

What do I pull to get the ABS light to go out in the mean time? Heading out on a weekend trip in the AM.

Click to expand...

Pulling the pump motor relay worked for me.

Wavey1 said:

What do I pull to get the ABS light to go out in the mean time?

Click to expand...

Black tape. :wink:

Tried that Jinks, didn't do it. Pulled the two 20A fuses too, ABS light still on plus the TCS. I guess once it throws a code it's on.

Wavey1 said:

Tried that Jinks, didn't do it. Pulled the two 20A fuses too, ABS light still on plus the TCS. I guess once it throws a code it's on.

Click to expand...

Pull the clock fuse first to clear code, then try pulling the pump relay prior to starting. My abs never threw a code prior to me pulling it, the pump just ran all the damn time. Good luck. Pulling the abs fuse will def, throw a code so I would keep those in prior to ecu reset.

First, please read the error code. Never reset it before reading the error code whenever you saw any warning lights.

Every time when you re-start the engine, it will re-start the ABS/TCS controllers and if the system is functioning properly after re-start, it won’t trigger the ABS/TCS lights even with the error codes stored in the memory.

By the way, with the classic ABS and non-DBW TCS, pulling the Clock fuse won’t do anything. It won't clear the error code from these 2 controllers.
The backup memory is not powered through the Clock fuse for them. You will need to pull the ABS 2,3 fuse for reset purpose.

I’m afraid pulling the ABS pump relay will eventually trigger the ABS light once you no longer have enough pressure inside the accumulator unless you short the pressure sw.
You won’t be able to reach the pressure threshold within 120sec as there is no pump relay and thus, eventually you will trigger ABS code #1 .

So, first thing first, please read the error code.

As you are triggering the TCS light as well, very unlikely but please check the Orange connectors for each solenoids. Because of the combination used, you could connect them in a wrong way.
You should see green sleeve on each solenoid connectors. They are never connected each other but can be done by mistake as the connector combination allows it.
Make sure that for each green sleeved orange connector, the mating connector should not have the green sleeve.
You will trigger 7-* ABS error code for this.

Kaz

Thanks Kaz. Right, tried the clock fuse and no change, ABS light still on. The TCS light was just temporary with the two 20A fuses pulled, and is out now. I've had the pump relay and the two fuses out, with the car running, with it not running, in every possible combination, and the ABS light is still on.

But I don't see any way the 4 orange connectors for the solenoids, at the front of the ABS modulator, could be assembled wrong. They're all different plug configurations (plug shape and male/female) and can only go together one way. Also the individual harnesses to the solenoids are all a different color, and those are clearly different from the corresponding car harness plugs. But on your advice I'll check those again.

I'm heading out on a weekend trip, without ABS, and will have to address this next week and will read the codes before proceeding.

Ultimately, how do I clear the code and get the damn ABS light to go off?

This early ABS system is such crap, seriously considering just deleting it with the Pole2Flag kit, or popping for the SOS retrofit.

Yes, reading the error code (if multiple warning lights triggered, you must read all codes from each controllers) would help a lot.

Again, Clock fuse does nothing for the classic ABS.
It’s not in the ABS system at all.
You can only erase the error code from classic ABS by removing the ABS2,3 fuse, disconnecting the battery or removing the 2 connectors from the ABS controller behind the glove box.

If your ABS light stays On immediately after restarting the engine AND even before start moving the car, your issue is very likely to be detected at the time when you turn the IG key into P2 – ON position, just before cranking the engine. Reading the error code will tell us more story.






Speaking of making mistake on reconnecting the orange connectors, can you tell which photo is the correct one and the one with the mistake?

As you can see, you can connect all 8 connectors in multiple ways if not careful.

I already knew several owners triggering ABS warning lights with this mistake.
If you take your time with good lighting, you can minimise the chance of making mistake.
However, if you try reconnecting these connectors in a hurry with limited space available or aftermarket parts obstructing your vision, easy to make wrong connection.

When you are back, let us know all of the error code.


Kaz

OK, returned. I haven't run the codes yet but here's where I am.

1. I pulled the ABS 2,3 fuse (#32 in the fuse block) while I worked on the rest, to clear the codes. I figured if I threw a code again I'd check it then.

2. I double-checked the solenoid connectors and everything was in order. BTW, on my car each solenoid harness is a different color (1 each green, gray, yellow and tan) so they're not all green. Each solenoid connector was/is connected to it's proper corresponding connector from the car harness. However I see what you mean now Kaz - it WOULD be possible to connect two harness connectors together or two Solenoid connectors together.

3. I installed Joe's test harnesses again and ran through the solenoids. Same result as before - just a click, nothing happening in the reservoir. However if I run the pump for 15-20 seconds to pressurize the system, the fluid level drops very slightly. Then when I activate any of the solenoids, I hear a faint "pphhhttt" sound and the level comes back up. This is the same for all 4 solenoids. So it seems that running the pump does pressurize the system to some degree.

4. I checked continuity at the pressure switch. If I run the pump as above and do not activate any solenoids, I have continuity so the switch is closed. If I activate a solenoid (relieving the pressure?), I do not have continuity.

I buttoned everything back up and started the car. Ignition on - all dash lights on as normal. Start it, all lights out as normal. No ABS light.

Haven't driven the car yet but I'm betting it will be the same as before - as soon as I get up to speed the pump will run for 10 seconds or so, then run occasionally while driving, and the ABS will seem to work, albeit probably on the weak side. I'll confirm that when I get a chance to drive it, and if it throws a code again I'll check that. But it never threw a code before I tried to exercise the solenoids.

I'm thinking I probably do have a weak accumulator. The weird thing is that running the pump creates enough pressure to close the pressure switch, but not enough to effectively exercise the solenoids. I don't get it. Feedback anyone?

Wavey1 said:

OK, returned. I haven't run the codes yet but here's where I am.

1. I pulled the ABS 2,3 fuse (#32 in the fuse block) while I worked on the rest, to clear the codes. I figured if I threw a code again I'd check it then.

2. I double-checked the solenoid connectors and everything was in order. BTW, on my car each solenoid harness is a different color (1 each green, gray, yellow and tan) so they're not all green. Each solenoid connector was/is connected to it's proper corresponding connector from the car harness. However I see what you mean now Kaz - it WOULD be possible to connect two harness connectors together or two Solenoid connectors together.

3. I installed Joe's test harnesses again and ran through the solenoids. Same result as before - just a click, nothing happening in the reservoir. However if I run the pump for 15-20 seconds to pressurize the system, the fluid level drops very slightly. Then when I activate any of the solenoids, I hear a faint "pphhhttt" sound and the level comes back up. This is the same for all 4 solenoids. So it seems that running the pump does pressurize the system to some degree.

4. I checked continuity at the pressure switch. If I run the pump as above and do not activate any solenoids, I have continuity so the switch is closed. If I activate a solenoid (relieving the pressure?), I do not have continuity.

I buttoned everything back up and started the car. Ignition on - all dash lights on as normal. Start it, all lights out as normal. No ABS light.

Haven't driven the car yet but I'm betting it will be the same as before - as soon as I get up to speed the pump will run for 10 seconds or so, then run occasionally while driving, and the ABS will seem to work, albeit probably on the weak side. I'll confirm that when I get a chance to drive it, and if it throws a code again I'll check that. But it never threw a code before I tried to exercise the solenoids.

I'm thinking I probably do have a weak accumulator. Feedback anyone?

Click to expand...

Sorry if my post were not accurate, I would listen to @Kaz on this issue. For some reason, when I disconnected my pump relay the abs was disabled without warning lights. But it would not surprise me if it was disabled somewhere else. Ever since I bought the car, the pump would chatter. But it used to only do it when cold and on the first approach. I feel your frustration on the abs. It is a freaking nightmare and updating it is higher than a new cost of wheels. At least the dash lights are out! The abs is another reason collectors will prefer later models. I guess the Oem upgrade is worth it's weight though.
Your issues sound exactly like my own.

If I can nail it down to the accumulator, I'm willing to pop for that if it will really fix it. $88 to recharge, or I found a good used part (cost unknown yet), or they're still available new @ $500 +/- which included the pressure switch I think. Thanks for starting this thread Jinks and I hope it's OK I jumped in.

Just drove it again and it's what I expected, back to square one before I exercised the solenoids the first time.

No ABS light, pump runs for 5-6 seconds first time out. I hit the brakes 5 times on loose surfaces and the ABS seems to be working - pulsating in the pedal and not locking up, then the pump runs for 2-3 seconds every time.

So, GraemeD, Scrapdog2Grand, Kaz, still pointing to a weak-charged or discharged accumulator, correct?

Wavey1 said:

Just drove it again and it's what I expected, back to square one before I exercised the solenoids the first time.

No ABS light, pump runs for 5-6 seconds first time out. I hit the brakes 5 times on loose surfaces and the ABS seems to be working - pulsating in the pedal and not locking up, then the pump runs for 2-3 seconds every time.

So, GraemeD, Scrapdog2Grand, Kaz, still pointing to a weak-charged or discharged accumulator, correct?

Click to expand...

That ^^ is what it is sounding like, you cant compress liquid, this is why the pressure builds quick and you will not get much fluid when relieving pressure, as well as the pump slowing rather quickly..

In Kaz photo I believe he was referring to what is called a soft set connector, they are not plugged in completely causing open or intermittently open circuits. And yes you can also plug them into each other :O

That's what I'm thinking too Joe, dead accumulator. My connectors are nice and tight. Thanks!

Double post

If you can measure the amount of high pressure fluid stored inside the accumulator, it will be straight forward diagnosis.
This is where the T-wrench becomes handy as it has measuring indicator on the side. Seems like it's discontinued in US.....

If you have access to deep offset (like 75deg) wrench (I think it was like 12point 9mm or something), you could carefully loosen that square shaped special bleeder without T-wrench and attach fluid collecting tube at the bleeder end but you are dealing with super high fluid pressure so be careful.

From what you wrote so far, you may have multiple issues.....
As you are able to close the pressure sw, you are achieving the targeted pressure threshold with at least some nitrogen gas left inside the accumulator but with unknown amount. Possibly just small amount of gas left behind the bladder.
Some of the solenoids could be sticky and not releasing much fluid back to the reservoir when you activated them despite you had enough high pressure fluid at the accumulator.
Your ABS pump could be very tired that it can’t pressurise the system efficiently within the specified time frame once the pressure sw was switches off.

Again, measuring the amount of high pressure fluid and reading the error code will reveal lots of things.

If the ‘kick back’ is not strong enough and weak at the brake pedal when ABS is triggered, you have lots of air inside the ABS piston side of the high pressure chamber that you can’t flush using the danoland method.


Kaz

OK, thank you very much Kaz! This all makes perfect sense now.

I will measure the fluid in the accumulator. I'll have to try alternate tools to the T-bleeder, unless I can borrow one somehow. That tool is apparently NLA everywhere - discontinued by Honda in Japan, I checked several Japanese sources with no luck, and any remaining are in inventory somewhere that I can not locate, or in private hands.

I'm thinking it would be possible to have a machine shop gun-drill through the length of a short 1/4"-drive extension (which has a square socket on one end that will fit the bleeder), weld a nut on the other end, then fit a tube to direct the fluid into a container. Or just do it the sloppy way and let it drain to a pan on the floor, but that could be hard to measure accurately.

However I'm also thinking I may not have that much pressure to deal with if the accumulator is shot. I'm really thinking it's going to be a bad accumulator which will be a relatively easy fix. But if I have to get into rebuilding the modulator with Warren's kit (which I have), and then maybe replacing the pump, I may as well do the upgraded system.

I just used a plastic tube/hose to bleed it as mentioned by Kaz, just be careful to slowly release the pressurised fluid by unlocking the bleeding screw in small angle and not in a full turn...

From what I have done recently on my friend's 94nsx imported from UK, it has completely dead ABS system and turn out it not only has a burnt pump motor, but also the pump's internal parts were all sticked together, after disassemble the pump mechanism there is a copper mesh filter need to be cleaned as well

I found that a 9mm, 12-point box-end wrench will fit the bleeder, so I'm going to try that with a tube into a measured container.

I've also been wondering if there was any way to service the motor or pump to get it to run a little quieter., and your photos help. Seems like it would be easy enough to do along with the accumulator. Thanks!

OK, I ran the pump to pressurize the system and opened the bleeder. Got *maybe* 10cc of brake fluid, so it sure looks like the accumulator. I'll order one tomorrow. I went ahead and ran the pump with the bleeder open and flushed new brake fluid through the system until it was clear. Replacing the accumulator looks fairly easy. I guess I'll have to bleed the new one without the T-wrench though. I also ran the codes and nothing was stored, but I had cleared them last weekend. I'll run through the solenoids again after that, and hopefully I'll be back to everything working, at least as well as it ever did. Thanks for everyone's advice!