ABS Relay 1 problem - brake accu?

Does the Motor Relay 1 click when you tell Techstream to activate it?

 

So in this condition does the car start does the car ready does the car have all the amber lights on like the brake pump is bad just curious? With no noise from the pump I would assume you have a very hard pedal or no brakes at all or you need two people to stand on the pedal or something when my accumulator was failing I had all the amber lights on on the dash but my pedal was great and I drove for almost a year like that until it finally completely failed.

 

Can you post a picture of the skid ecu? I am having an issue and was wondering if it's the same. I also have blink code.

My codes are (!) 52 and 57. ABS 42.
What does it mean?

 

Sounds about right mine was running all the time but wasn't making good pressure in my '05 so I had a hard pedal that two people had to stand on to stop the car so we stopped driving the car. Then in my '09 the same thing was happening The pump was running a lot not all the time but when I get out of the car I'd be in the house and hear it still running before it cut off 2 minutes something and all the lights were on on the dash that normally come on for the accumulator or the big brake problem where the pump is always running. At that point I still had a good pedal and everything was working basically as it should but the pump running a lot this went on for almost a year and a half and then a caliper failed and then the brakes failed except for one caliper in the front working. And at that point I changed out the accumulator actuator right behind the inverter and then all the lights went away and everything worked like when I first bought this 09 model car and I've left it alone since then I did not bleed with tec stream or any of that .

 

dolj answered that question for you in your other thread, here.

 

If it were my car, and I confirmed the relay was clicking, I would be looking in the wiring diagram to see the path for motor current through that relay, to see if I could use my meter and find the first point where the voltage did not appear. If the voltage appeared all the way to the brake actuator but the pump did not run, I would conclude the problem was within the actuator assembly. (In a Gen 2, there's no strong need to distinguish the actuator from the accumulator, as that generation combined them in one assembly anyway.)

Toyota Service Information and Where To Find It | PriusChat

 

Naturally, if you've confirmed voltage at the relay pin 5, it would make sense to next confirm voltage at pin 3 when the relay is closed.

If that is confirmed, then A2 pin 2 would be the logical next place to check. Yes, it may be in a hard place to reach. But certainly less hard than replacing the actuator assembly, which would be the next step if you don't check for a wiring fault first. And the work of reaching it is part of the work that would be necessary for actuator replacement.

The benefit of checking the wiring first is it saves you the effort and expense of replacing the actuator if the actuator isn't the problem.

 

The windshield does not need to be removed for access, only the windshield wipers and the cowl. This is a step that is at the start of so many procedures under the hood that it is like "chop one onion" at the start of a recipe. I don't do it in a workshop, but in my driveway.

When the brake system is in good condition, the drop of pressure when the brakes are not used is very slow, on the order of hours.

 

If you think about it, the schematic is a drawing of the system when it worked. What happens when something fails is that, somewhere in the car, something has become different from what the schematic shows. Whether that's in the wiring outside the actuator, or the wiring or connections inside the assembly, it's still weird when you're looking at the schematic.

Hmm, I have only just noticed that the diagram you posted does not show the motor resistor. The difference between the motor 1 and motor 2 circuits is that circuit 1 includes a resistor (so relay 1 is used to run the pump at a quieter speed). The resistor is located inside the cabin, under the dash, near the left corner under the windshield.

What you posted came from the repair manual, where simplified wiring drawings are often included in diagnostic sections for convenience. They are sometimes missing details from the actual wiring diagrams, which are in a separate manual.

Your diagram shows the green wire from the relay pin 3 routed directly to A2 pin 2.

In reality, the green wire runs through the firewall to pin 2 of connector IP1, whence a black wire continues to pin 2 of B19 (the resistor). From pin 1 of the resistor, a white wire runs back to IP1 (pin 1) where it becomes a pink wire that runs to A2 pin 2.

So a few things more to check.

In this thread, you will see that post #39 describes how to reach the resistor with less work than removing the dash top:

brake actuator resistor | PriusChat

Internal fluid leakage, by the way, isn't always a problem with the pump. There are many valves inside the actuator, which can eventually fail to seal completely when closed, leading to pressure loss.

In a Gen 2, it is not especially important to distinguish between pump/accumulator/actuator problems, as they are all one assembly. In Gen 3 it becomes more important, as there is a choice of which assembly to replace.

 

Yes, that's the animal.

 

I would remove motor relay (1) and check voltage at pin 3 when motor relay 2 is commanded on. If BM1 and the resistor are ok, then you should have 12V at pin 3. If that is ok then I would carefully jumper relay pin 3 to 5 and see if the pump runs.

Posted via the PriusChat mobile app.