Brake Gremlin

[werminghausen]

Now I am excited!

I was getting ready (mentally) to pull this beloved hydro booster for dismantling but wanted to put the fuses/relays back.
After testing the ABS Sol Relay I put this part back and expected the alarm, as usual.
But to my surprise after I put the key into ,ignition' nothing happened- no alarm sound.... simply the ABS/TRC/VSC lights stayed on. That did not happen in a long while.
Now guys- fasten seat belts-I started the engine put my foot on the brake and was expecting the alarm sound now..... but nothing happened.
In fact after about 30 seconds the lights went off! ABS/TRC/VSC cleared. I thought I was dreaming.

Well I did not drive but felt a bit confused...positively confused. Could it be that this relay was acting up and cause such a headache?

Well before I am getting overexcited.... what kind of testing do you suggest to confirm that something changed.
- Could I read different ABS codes now (in case something changed) or would the codes still show up. Do I need to reset the ABS codes in that case and then drive and test again?
- Should I drive and use the brake and test all the situations (as much as I can), see if all works?
Martin

 

[SocalSam]

Now I am excited!

I was getting ready (mentally) to pull this beloved hydro booster for dismantling but wanted to put the fuses/relays back.
After testing the ABS Sol Relay I put this part back and expected the alarm, as usual.
But to my surprise after I put the key into ,ignition' nothing happened- no alarm sound.... simply the ABS/TRC/VSC lights stayed on. That did not happen in a long while.
Now guys- fasten seat belts-I started the engine put my foot on the brake and was expecting the alarm sound now..... but nothing happened.
In fact after about 30 seconds the lights went off! ABS/TRC/VSC cleared. I thought I was dreaming.

Well I did not drive but felt a bit confused...positively confused. Could it be that this relay was acting up and cause such a headache?

Well before I am getting overexcited.... what kind of testing do you suggest to confirm that something changed.
- Could I read different ABS codes now (in case something changed) or would the codes still show up. Do I need to reset the ABS codes in that case and then drive and test again?
- Should I drive and use the brake and test all the situations (as much as I can), see if all works?
Martin

It's not unusual for electrical components to lose contact. Pulling and re-seating components is enough to remove oxidation which can cause resistance to rise enough to interrupt operation. It is also possible that more jiggling of the fuse box resulted in pins seating or wires becoming un-shorted. Whatever the case may be, it's great news you have the issue isolated and if the fault returns, you know where to look.

I guess I am more shade tree than most. Understanding is nice but sometimes I take it on faith that doing this will result in that. If a fix results in better operation, I go with it and drive until it breaks again. I do have a process that I follow. I look for the easiest fix first. Easiest is usually the cheapest so there is incentive here. When reviewing codes, I look for root cause which in this case was electrical. Other codes are cascading and clear by themselves.

 

[AuSeeker]

Now I am excited!

I was getting ready (mentally) to pull this beloved hydro booster for dismantling but wanted to put the fuses/relays back.
After testing the ABS Sol Relay I put this part back and expected the alarm, as usual.
But to my surprise after I put the key into ,ignition' nothing happened- no alarm sound.... simply the ABS/TRC/VSC lights stayed on. That did not happen in a long while.
Now guys- fasten seat belts-I started the engine put my foot on the brake and was expecting the alarm sound now..... but nothing happened.
In fact after about 30 seconds the lights went off! ABS/TRC/VSC cleared. I thought I was dreaming.

Well I did not drive but felt a bit confused...positively confused. Could it be that this relay was acting up and cause such a headache?

Well before I am getting overexcited.... what kind of testing do you suggest to confirm that something changed.
- Could I read different ABS codes now (in case something changed) or would the codes still show up. Do I need to reset the ABS codes in that case and then drive and test again?
- Should I drive and use the brake and test all the situations (as much as I can), see if all works?
Martin

I wouldn't count my chicken before they hatch....clear the codes, drive it as if this all never happened and see if the lights and alarm/codes come back, if they don't, you have by exploring possible causes found the faulty component/connection, then it's time to celebrate and rejoice!!

If it's just a fluke and it all comes back you're no worse off than you were.

 

[werminghausen]

Aye, I'll try an clear the ABS codes.... need to read the manual, I guess.

On another note. I was driving tonight and T4R behaved as if nothing happened (no alarm bells, no dash lights).... except for the not so great braking power but not any worse than it was before all this trouble started.
You are correct... don't count the chicken too early.

 

[werminghausen]

hi Sam,
I like your approach as well.
It is a bit of both.... trying to use some logic : finding the correct hierarchy of the failure code -root cause. Then some testing but fooling around is also valid. Who the heck should I know that a little contact problem is causing such a headache.
No question about this - the electronics of these cars are a true and honest gremlin. May they show up... but not that often.

Honestly I have another gremlin to solve but less on the front burner than the brakes: It is the back hatch that is not working any more... Maybe I need to wiggle the relay?

I'll try and clear the ABS codes on the weekend and then wait.

Thank you all who helped me finding a way out

Best, Martin

 

[AuSeeker]

hi Sam,
I like your approach as well.
It is a bit of both.... trying to use some logic : finding the correct hierarchy of the failure code -root cause. Then some testing but fooling around is also valid. Who the heck should I know that a little contact problem is causing such a headache.
No question about this - the electronics of these cars are a true and honest gremlin. May they show up... but not that often.

Honstely I have another gremlin to solve but less on the front burner than the brakes: It is the back hatch that is not working any more... Maybe I need to wiggle the relay?

I'll try and clear the ABS codes on the weekend and then wait untils something else is happening. Thank you all who helped me find somerthing:
There is a Geman saying : Auch die dümmste Sau findet mal ein Eichele.
I guess this is true in my case.

Best, Martin

In English there's a similar saying...."even a blind squirrel finds a acorn once in a while"

 

[SocalSam]

In English there's a similar saying...."even a blind squirrel finds a acorn once in a while"

Blind squirrel can find a shade tree.

 

[SocalSam]

...I have another gremlin to solve...back hatch that is not working any more...Maybe I need to wiggle the relay...

No power to hatch actuator? Outside release switch are known to go bad in our trucks. Could also be hatch module but check the switch first.

Or does actuator run, fail to unlatch, and then cycle back to locked position? Remove inside plastic trim. Locate release bar on actuator and open hatch. Remove and reverse catch loop to present clean side to actuator.

 

[werminghausen]

Thanks Sam

Oh.. that bad hatch door:
what works: opening and closing the hatch is the only thing that works
What does not work: All other functions are not working: NO Window up/down, No Wipers, No Window Washing, No Defrost .

I had really bad periods of time in wet summer seasons (never in winter) when the door locks acted up. I believe it all started from the rear hatch door lock. What happened was that during these very wet times all of a sudden the door locks started clicking for quite some time, maybe 5 minutes in a row: lock/ lock/ lock etc. During these events all the door locks were clicking like crazy.
The greatest of all gremlin was when on top of the lock clicking the rear window started rolling down without pressing a button.... during these crazy wet times the lock clicking and window rolling could happen at any time, during driving and during parking.

Until this winter, despite the crazy clicking and window rolling...the rear hatch door had all the functions working. That changed last fall when all of a sudden the window would not roll down any more, no wipes, no washing and no defrost.

Any solutions?

 

[SocalSam]

IIRC correctly, Fob receiver is located in the upper rear driver pillar next to the hatch. Start there. Also research the hatch module. It may be bad from the elements.

 

[werminghausen]

Thanks Sam,
rear hatch: I don't understand the connection between the fob and the rear door functions (except for the rear door lock).
I gave up using the fob after that crazy clicking (because it seemed to add to the craziness) . I am using the good old keys only, since 3 years, and I am fine with this.
The self locking mechanism is inconsistent -when you go from D into P the door locks should open and if you shift to D they should lock. That mechanism does not always work, sometimes the doors do not lock when shifting into D. When parked at times the car locks itself when I leave the car unlocked overnight at home and at other times (like in winter) the car stays unlocked overnight (no need to lock the car in our remote area).
Rear Hatch- that ECU in the rear hatch could be the trouble maker. I had it once removed and inspected and all looked brand new inside... but who knows.
If you think there is a great chance that this ECu is bad I'll oder another one. That rear door must work... I like the window rolling down in the rear.

 

[werminghausen]

Brake Gremlin Continues.

I was driving today and ... the alarm started again! Alarm was starting several time without touching the brake at all. The alarm has nothing to do with any brake action!

Each time I stopped and wiggled the green ABS relay and the alarm sound stopped and dash lights cleared after restart.
But the silence does not last... after a few miles the circus started again and each time I could repeat the short cure: I wiggled the relay and I could continue.
I have no explanation how the wiggling can clear the alarm except for: The ABS Relay is bad.
The relay must have been activated somehow..... but how?
If I can wiggle and the relay becomes inactive again... the something gets tuck and then unstuck. I don't think the trigger for the activation is the control circuit... simply because the activation stops with the wiggle (if the control circuit would be active there would be no way to make the relay inactive with wiggling).

I also don't know how this relay is triggering the alarm. If the ABS is working as it should during braking (which it does, I tested it yesterday- works fine), then there is no alarm at all. So the active relay does not trigger the alarm during ABS braking action (car braking on slippery ground)
There must be something else triggering the alarm but I don't know what this is:
Does the ECU check back with the ABS sensors or brake action (yes/no) if the relay is triggered? If the ABS sensors are not asking for ABS brake action or if the brake is not touched with the ABS relay active... then the alarm goes off? Could be that the alarm is then telling that something is fishy.

Anyhow I have ordered another green ABS relay...

Another thing I wanted to ask with all these elec-tricky problems I have: Would it be a wise idea to check and redo all the main ground connections: Battery to chassis, to engine block etc. especially because my T4R is so rusty (I had to weld a lot of steel into that poor frame of mine- there is a price to living in the rust belt and driving a car with super poor steel quality (I have never seen so much corrosion in a car frame as with the T4R)
Is there some information how to pursue redoing the ground connections?

Best, Martin

 

[werminghausen]

I removed the green Relay again and tested it extensively. It works perfectly fine.
Weird thing is: With the green relay removed from the fuse box I cannot trigger the alarm if I artificially create a short at the receptacle of the relay.
The ECU knows that the relay is removed (the dash lights ABS/TRC/VSC/ light up).
I wonder: How does the ECU know that there is no relay in place??? What is the magic that the ECU knows? Is there an ever so tiny current sent through the control side of the relay (between pins 3 and 4) that is measured and that tells the ECU that the relay is in place but does not trigger the relay?

If I cannot trigger the alarm by connecting the relay receptacle for pins 1 and 2: Does that mean that the relay is not involved in triggering the alarm ... But I can stop the alarm through this relay.....?

 

[werminghausen]

I was just reading the current ABS codes 1-4.
Before I erased the codesn I had 8 failure codes.
I listed them all below and marked the 4 current ones.

1) C0278 open/short Circuit in Antilock Brake System Solenoid Relay Circuit
2) C0279 Battery Short Circuit in Antilock Brake System Solenoid Relay Circuit
3) C1223 Malfunction in Antilock Brake System Control System
NOT [C1246 Malfunction in Master Cylinder Pressure Sensor]
NOT [C1252 Hydro-Booster Pump Motor Malfunction]
NOT [C1253 Hydro-Booster Pump Motor Relay Malfunction]
NOT [C1254 Pressure Switch Circuit]
4) C1256 Accumulator Low Pressure Malfunction


What I am reading now is that there are 3 events
A) Solenoid Relay Circuit problem (open circuit/short in circuit)
B) Antilock Brake System Control System (Malfunction)
C) Accumulator low pressure malfunction.

I am not certain what the ABS control system is but it could be the ECU (Skid Module ECU)?

If so I could probably buy a good used Skid Module ECU (Toyota 4Runner ABS TRC VSC Traction Control Skid Module 89540-35320 5626)

I know I am starting throwing parts at this problem but what else can I do?

The ABS Skid Control ECU looks like in the picture and on the label I see the note:

"Initialize the VNC computer (I am assuming the VNC computer is this very skid module?) according to the repair manual before servicing.
Service by authorized dealer only (I love these kind of instructions)

So it seems there is a procedure described in the manual (which I don't have). Is the installation of the the Skid module doable for me?

Need help here.

Best, Martin

 

[MikeinNH67]

If it were me, I would replace all the relays in that circuit with new ones or at least the solenoid one. The relays are cheap and it is known that some of the OEM ones stick in the closed position. That solenoid relay probably cycles pretty often. I'd start there, need some known good stuff. The malfunction code would probably be there if that relay is acting odd.

If that fixes the issue, then at least you have your old unit for parts. Maybe it's better than the "rebuilt" one.

As for the hatch, some things back there will not work if the system doesn't think the window is all the way up. You could try some things like using the key in the hatch to lower/raise the hatch and could pull the inside cover to unplug the controller in the hatch to reset it. The hatch glass moves on a pulley system that could be locked up. I replaced my whole setup with a used one someone was selling.

 

[SocalSam]

Replace relay. It supplies power to solenoids. Or perform click test and check current side for continuity. It's a good idea to open up relay and clean up current side contacts. If relay passes, then issue lies beyond the relay.

Do dash lights and CEL some on immediately on key on or do dash lights come on after driving a little? The former is a POST or initiation error, the latter is likely bad sensor input.

C0278 and C0279 indicate relay and power issue.
C1223 indicate unresolved ABS issue and goes away when root cause is fixed.
C1426 is Master Cylinder Pressure Sensor which is part of the ABS Hydraulic Control Actuator. That's the $1.4k part we are trying to avoid.

You need to clear C0278 and C0279 first. Best case scenario is solenoids are not getting power which is causing C1426 code.

 

[werminghausen]

Replace relay. It supplies power to solenoids. Or perform click test and check current side for continuity. It's a good idea to open up relay and clean up current side contacts. If relay passes, then issue lies beyond the relay.

Do dash lights and CEL some on immediately on key on or do dash lights come on after driving a little? The former is a POST or initiation error, the latter is likely bad sensor input.

C0278 and C0279 indicate relay and power issue.
C1223 indicate unresolved ABS issue and goes away when root cause is fixed.
C1426 is Master Cylinder Pressure Sensor which is part of the ABS Hydraulic Control Actuator. That's the $1.4k part we are trying to avoid.

You need to clear C0278 and C0279 first. Best case scenario is solenoids are not getting power which is causing C1426 code.

Thanks Sam:
You and Mike both point to the relay (even though I don't understand how the relay may trigger the alarm since I cannot replicate the event by simply
short the relay's output side [contacts 1 and 2], connect the 2 socket leads with the relay removed. The electronics must be really clever.


C0278 and C0279 indicate relay and power issue.
C1223 seems related.
I'll try and get new relays, at least the Green Relay (U180 that runs the solenoids.
old Contacts look brand new, but I will get the burnish tool and clean
contacts and test with the old relays again.
At least the brakes worked for a day or so before the circus started again.

C1426 is Master Cylinder Pressure Sensor is a hardware piece...a sensor.
Lets hope this code is NOT unrelated to the first 3 codes?

Maybe no one really knows what is going on inside the ECU and therefore hard to analyze what is happening?

I could try and remove the pressure sensor and clean it out... if that is the issue. If it does not solve the issue... get a new pressure sensor.... or a new ABS hydro booster when I am desperate enough.

Any information from you guys is good information. ( I am a mechanical engineer trained at the Mercedes/Maybach factory in Germany in the 70s...so that was way before electronics took over... all mechanics I can easily understand and electrical... electronics- not so much)

Martin

 

[werminghausen]

If it were me, I would replace all the relays in that circuit with new ones or at least the solenoid one. The relays are cheap and it is known that some of the OEM ones stick in the closed position. That solenoid relay probably cycles pretty often. I'd start there, need some known good stuff. The malfunction code would probably be there if that relay is acting odd.

If that fixes the issue, then at least you have your old unit for parts. Maybe it's better than the "rebuilt" one.

As for the hatch, some things back there will not work if the system doesn't think the window is all the way up. You could try some things like using the key in the hatch to lower/raise the hatch and could pull the inside cover to unplug the controller in the hatch to reset it. The hatch glass moves on a pulley system that could be locked up. I replaced my whole setup with a used one someone was selling.

Thanks Mike,

I'll get replacement for the relays, thats easy and see where this goes.

hatch: yes I heard about this sensor...sounds complicated. The glass is up, all the way.... when I push the button for the window I can hear a click... like a relay clicking but no motor. I also heard that I can operate the window with the key but that does not work either on my car.

So maybe that ECU is cooked...Can I replace that ECU simply or do I need to reset/program that board somehow?

Martin

 

[SocalSam]

External contacts are not the issue. Take relay top off and clean internal circuit side contacts. They carry current and can arc which wears them out or causes carbon deposit. Click test is applying 12V to the control poles. This tests the coils which magnetizes to close circuit side and allows current to pass to the solenoids.

 

[werminghausen]

Thanks Sam,

Did I understand correctly, that the internal contacts can arc. The contacts would look like this and that could cause my symptoms (brake alarm)?
Here is a picture of my relay contacts and I found a picture of a good and bad contact.