[chrisaw]

Hello!

I've got a Toyota RAV4 2019 (Excel - UK spec) and after installing a 13 pin towing wiring kit my fuel door no longer opens when I press the button.

I have done some research on this and here's what I know so far:

• Using my power probe - there is no 12V present on the positive wire going in to the fuel door actuator
• If I inject 12V in to the fuel door actuator positive wire - the door pops right open
• When pressing the button to open the fuel door - my power probe (which has a poor version of an oscilloscope embedded) shows a pulse on the wire
• The 10A fuse seems to be perfectly fine and I have tried to replace it but this makes no difference.
• Disconnecting the 13 pin wiring from the vehicle again makes no difference.

What I really need to know is where the other end of the wire for the fuel door actuator connects to the car - then I can probe that side and see if the relay is trying to pass 12V to it from that end.

I really don't want to take this to Toyota because they'll no doubt bend me over for it and it's likely something easily fixed.

Any help would be greatly appreciated!

 

[chrisaw]

Bit of an update at my end - it looks like the two connectors I need to test are:

• N6 fuel lid with motor lock assembly connector
• A24 ECM connector

This is useful and I've found the N6 connector without any troubles but the A24 ECM connector I'm completely lost with - can anyone direct me? There's a LOT of connectors with a LOT of wires in each so struggling to find the right connector. I would trade my soul for a photo of the connector in question!

 

[crazyhorse]

This probably doesn't help.

 

[Mr_Flux]

There's a LOT of connectors with a LOT of wires in each so struggling to find the right connector.

It's got to be related to one of the wires that were touched by adding the harness, no? Should at least narrow it down to one of the 13 pins. Maybe see if one of those pins lights up with power when the button is pushed; if you simply got the wrong wire on something you could be applying fuel door power through the towing harness and your fuel door may get trailer brake power.

 

[chrisaw]

I disconnected the 13 pin harness completely and sadly no change.

What I have found is that ultimately the issue is one of two things:

1. The relay responsible for sending 12V to the motor isn't doing so or
2. The wire responsible for delivering the 12V to the motor has a break / short somewhere.

I have stripped back the wire as much as I can without completely dismantling the car and no dice.

What I REALLY need to know is exactly where the "FUEL DOOR OPN RELAY" is so I can test it but trying to find that info is very difficult. I can see roughly that it's somewhere behind the left side of the dash but I don't see any relays behind the glove box (my car is RHD so opposite to most of yours and the relays really are on the left under the glove box! )

If anyone can tell me where the relay is for the fuel door opn relay I'd be absolutely delighted!

 

[crazyhorse]

Does this website help?

Fuse box diagram Toyota RAV4 5G and relay with assignment and location (fuseandrelay.com)

 

[Mr_Flux]

I'm not certain that there is or isn't a relay, and this all that my wiring diagram details for a 2020 Hybrid:

If it's just a direct wire you could probe it externally through an extension cord and see if that pin delivers the needed power bypassing everything else between them. US model my fuel opener switch is down by the buttons for the heated steering wheel, auto brights, etc, so your location checks out just on the other side. Have you read the description on the bottom of all three fuse panels? I'd think if any of the relays were for this door it'd be labeled.

 

[chrisaw]

Thanks all for the help!

Sadly so far I've been unable to find a physical relay and I'm quite mystified because I certainly hear a loud click (like a relay activating) when pushing the fuel door open button.

I've attached the diagram that the toyota-tech manual includes with the following key:

*A	for RHD	-	-
*1	FUEL LID OPENER SWITCH	*2	FUEL LID WITH MOTOR LOCK ASSEMBLY
*3	INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - FUEL LID OPN RELAY	*4	NO. 1 ENGINE ROOM RELAY BLOCK - FUEL OPN FUSE

What I could really do with is a picture or diagram of what a "Instrument Panel Junction Block Assembly" looks like - if anyone could point me in the right direction. No doubt this is a dumb question but I see SO many connectors under there that testing them one by one would take days and something tells me my wife wouldn't want to sit pressing a button over and over again for that long! D:

Tell you one thing - this would be SO much easier to diagnose on a LHD car - can press the button easily while looking at the wiring - for me it's damn near impossible and takes a good minute or so per connection to reach over and push the button!

 

[chrisaw]

Thanks all for the help!

Sadly so far I've been unable to find a physical relay and I'm quite mystified because I certainly hear a loud click (like a relay activating) when pushing the fuel door open button.

I've attached the diagram that the toyota-tech manual includes with the following key:

*A	for RHD	-	-
*1	FUEL LID OPENER SWITCH	*2	FUEL LID WITH MOTOR LOCK ASSEMBLY
*3	INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - FUEL LID OPN RELAY	*4	NO. 1 ENGINE ROOM RELAY BLOCK - FUEL OPN FUSE

What I could really do with is a picture or diagram of what a "Instrument Panel Junction Block Assembly" looks like - if anyone could point me in the right direction. No doubt this is a dumb question but I see SO many connectors under there that testing them one by one would take days and something tells me my wife wouldn't want to sit pressing a button over and over again for that long! D:

Tell you one thing - this would be SO much easier to diagnose on a LHD car - can press the button easily while looking at the wiring - for me it's damn near impossible and takes a good minute or so per connection to reach over and push the button!

An update from my end - I bought a cable "toner" and found the other end of the cable - woooo! Sent +12V down it and whatya know - cap flips right open. So yeah it 100% looks like a faulty relay which is a more annoying problem because I still have no idea where to find it. I suspect it's in the same part the wire plugs in to but that doesn't help much because it's pretty tightly stuffed in there and I suspect it's a "disassemble the entire dash to get to it" type thing. :/

 

[Mr_Flux]

Can you check that your fuel up button is actually passing power? You're sending 12v down the wire directly but it could be the button itself.