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Discussion Starter #21
At A43

Pin 6 - 12v is present regardless if pedal is pressed or not (Correct)
Pin 4 - Ground Confirmed Good
Pin 2 - 12v is present when pedal is applied
Pin 8 - Out puts 12v when jumped from Pin 2 and 12v seen at Pin 4 at Relay

The A43 Relay Assembly Looks like this:


I ground the relay at pin 4 and applied 12v at pin 2. Still no continuity between 8 and 6.

I believe this is the culprit. For now I have bypassed the A43 relay and jumped Pin 2 and 8. Brake lights work as they should.

I bought an OBDII scanner today from Harbor Freight on sale for $99. Reads ABS codes as well.

Pulled C code showing a malfunction in the ABS relay assembly. Go figure....
 

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Found the relay. No continuity between Pin 2 and 8. Can jumper 2 to 8 on the car side an receive 12v on pin 4 at the relay.
Did your brake lights come on with this jumper in place?

I ground the relay at pin 4 and applied 12v at pin 2. Still no continuity between 8 and 6.

Any other suggestions?
It looks like you have all the proper signals at the relay. If it really is a relay, and works as expected, you have proven it is defective. I guess you have three choices.


  • replace it with a new unit
  • adapt the wiring to accept a less expensive relay
  • jumper pins #2 to #8 (which reverts the wiring back to the earlier model years) and try driving the RAV to see if the brake lights work and the dashboard warning lights go off. They may still remain on if you damaged the Skid Control ECU earlier,

EDIT: Looks like you added the answers to some of these questions after I read it the first time.
 

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Discussion Starter #23

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I guess a standard SPST relay would work?

12VDC/40A SPST Automotive Relay : Automotive Relays | RadioShack.com

Car Side Pin ----------------- Relay Pin
Pin 2 -------------------------- Pin 85
Pin 4 -------------------------- Pin 86
Pin 6 -------------------------- Pin 30
Pin 8 -------------------------- Pin 87
At this point I am just assuming that A43 is a standard relay. When you removed it, did it only have 4 pins? The reason I'm asking is because I know the pedal switch also send signals to the Shift Lock and Skid Control ECMs. These connections are probably still made via A35 and your relay substitute should not affect them.

Your drawing looks correct. Perhaps you can use some common crimp connectors to make 4 short pigtails to adapt the connector to your Radio Shack relay. I would prefer to buy the OEM device before I would cut off the connector to use the Radio Shack substitute.
 

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Discussion Starter #25
At this point I am just assuming that A43 is a standard relay. When you removed it, did it only have 4 pins? The reason I'm asking is because I know the pedal switch also send signals to the Shift Lock and Skid Control ECMs. These connections are probably still made via A35 and your relay substitute should not affect them.

Your drawing looks correct. Perhaps you can use some common crimp connectors to make 4 short pigtails to adapt the connector to your Radio Shack relay. I would prefer to buy the OEM device before I would cut off the connector to use the Radio Shack substitute.
The A43 only had 4 pins.

You are correct that the pedal switch sends the Skid Control ECM and Shift Lock 12v via A35.

I have soldered leads to the Radio Shack relay and plan to use crimped connector to connect to the body side of A43.
 

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Discussion Starter #26
Rick, thank you again for all your help. PM me your paypal email and I'll shoot you a tip!

All done and everything is working!

My attempt at making the next ownerslife a little easir if anything should go wrong with the relay in the future:


 

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Rick, thank you again for all your help.
I'm glad it worked out for you, but I think you did most of the work yourself. It seems the information I provided from the 2007 manual may have only caused confusion.

I'm especially glad that you didn't cause any damage to the Skid Control ECM with the accidental 12v connection.

I hope you will become a regular member of these forums and provide your diagnostic skills to help others.

Rick
 

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Discussion Starter #28
I'm glad it worked out for you, but I think you did most of the work yourself.
Thank you!

Out of curiosity I opened up the A43 assembly, and it's definitely blown and definitely not a simple SPST relay.
Perhaps the voltage regulator went bad on it and over heated the circuit?

Wondering if I should bight the bullet and just replace it with an OEM part instead of my Radio Shack relay





On a side note, it appears that Pin 3 from the relay sends 12v to all three rear lights as well as Pin 2 (STP) of the the Skid Control ECU:

 

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I opened up the A43 assembly, and it's definitely blown and definitely not a simple SPST relay.
Perhaps the voltage regulator went bad on it and over heated the circuit?

Wondering if I should bight the bullet and just replace it with an OEM part instead of my Radio Shack relay
When you see a modification like this introduced from one model year to the next, you have to ask why. The wiring diagrams show it is the electrical equivalent of a SPST relay. That is why I thought it might have been added to reduce current through the pedal switch and increase it's lifespan. The only other reason that comes to mind is that it provides a regulated voltage to the LED brake lights to increase their life.

If you really want to replace it, there are members on this forum that seem to have a knack at finding discounted parts on the web.
 

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Discussion Starter #30
If you really want to replace it, there are members on this forum that seem to have a knack at finding discounted parts on the web.
I may have to search around.

I guess I could always solder in a 12v regulate after pin 8 of A43?
Though this seems redundant with the upstream 10amp "Stop" fuse

Are your 2008 tail lights LED?
 

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On a side note, it appears that Pin 3 from the relay sends 12v to all three rear lights as well as Pin 2 (STP) of the the Skid Control ECU:
It appears that there is no reason for that connection to the STP terminal, other than providing verification that the brake lights are actually on when the driver steps on the pedal or when the Skid Control ECU command the brake lights on during VSC takeover control. It is probably used to control one of the dashboard warning lights.

Where are you getting all these diagrams from?
 

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I guess I could always solder in a 12v regulate after pin 8 of A43?
Though this seems redundant with the upstream 10amp "Stop" fuse

Are your 2008 tail lights LED?
I don't think the fuse would protect the LED's from over-voltage. If you control the voltage across the LED's, then the current will also be limited.

Can you read the part number on the regulator? It may be a fixed regulator or it's output is controlled by the resistor values. It may be designed to output less than 12v.

I have LED brake lights on my 2008, and never had a problem with them. That is why I question the need for the added device. Perhaps the type of LED's were changed when they switched to the white taillight housings.
 

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Discussion Starter #33
Where are you getting all these diagrams from?
Check out JunBug's Profile and look a few visitor messages down:

http://www.rav4world.com/forums/members/32793-junebug.html

He's saved several different model year wiring diagrams and FSM's:

MyDrive - Ihr Schweizer Online-Speicher
Username: [email protected]
Password: Secret

I'm pulling the diagrams from the following:

2011 RAV4 Repair Manual (supplemental).rar
2011 RAV4 Wiring Diagram Manual

Can you read the part number on the regulator? It may be a fixed regulator or it's output is controlled by the resistor values. It may be designed to output less than 12v.
There are no markings on the VR. Any ideas of how to test the regulator for Voltage rating? I don't have a power supply.
Also, the VR only has 2 pins mounted in the PC board. The middle pin has been "chopped" off.
Odd, since that is typically ground? Perhaps they've grounded it through the board?
 

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I'm pulling the diagrams from the following:

2011 RAV4 Repair Manual (supplemental).rar
2011 RAV4 Wiring Diagram Manual
Thanks, I have those documents but I was only looking at the 2 page wiring diagram for the brake lights.

There are no markings on the VR. Any ideas of how to test the regulator for Voltage rating?
Also, the VR only has 2 pins mounted in the PC board. The middle pin has been "chopped" off.
Odd, since that is typically ground? Perhaps they've grounded it through the board?
You can't actually test the device, but perhaps you can find a friend, or take a "test drive" at the dealers, and measure the voltage at the brake lights.

All regulators need 3 leads to operate. Often the ground is connected to the metal tab, which is grounded to the circuit board (or heat sink) via a mounting screw. I don't see that tab in your photo. Without knowing the function of A43, I recommend replacing it with an OEM version to prevent possible premature failure of the LED's.

 

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It seems like an unusual move for Toyota to replace a dependable mechanical relay with an electronic switch version. Perhaps the black plastic component in A43 is simply a transistor, but that would require 3 pins as well.

If you are confident that A43 only served as a relay, then your home brewed repair should be fine.
 

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Discussion Starter #37
It seems like an unusual move for Toyota to replace a dependable mechanical relay with an electronic switch version. Perhaps the black plastic component in A43 is simply a transistor, but that would require 3 pins as well.
I am fairly confident that it is mearly functioning as an SPST relay.

The preiviously provided link calls the assembly out as a 12V 30A Fan Relay.

Perhaps an electronic style relay was chosen due to location? The mechanical relay that I have used makes a noticable click each time the brake pedal is pressed. As most mechanical stlye relays do. Could be annoying to some.
 

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This looks like the same problem I am facing. First, my brake lights were on all the time, now they won't come on at all, and I have the ABS and traction control (VSC) lights on, on the dash. My first hunch was a bad brake pedal switch, so I got one from Rockauto for $20, but it made no difference. When I jumper the OBD pins 4 & 13, and turn the ignition on, I get a code 46 on the ABS light and 43 on VSC light. My local mechanic told me his OBD indicated a defective Master cylinder pressure switch, but I am skeptical. My next step will be to check the A43 relay.
 

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Yup, it's smoked, and looks just like the one Overlord475 photographed, with burn marks, etc. I tried the link he provided for a supplier of the part, but the Chinese supplier wants me to buy a minimum of 5 at a time, and my dealer (who couldn't find the part at first because --she said--it was a Lexus only part number) can order one from Boston for $100. I just found a used one on eBay for $31 including shipping, and ordered it.

By the way, it looks like mine had corrosion in it, and then I just remembered a couple weeks ago I left the windows down and it rained overnight. I am guessing that is what caused this issue, though I don't know how rain could've worked it's way under the dash and inside the relay cover.
 

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Let us know if the replacement A43 solves your problem.

I don't think the OP (Overlord475) has been on the forum since his problem was solved so we don't know if his improvised solution continued working.
 
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