2020 SR5P. Searched everywhere for answer. My Diode Dymanics SS3 Fogs worked fine for years then started blowing fuse. Culprit was the driver side pod. I removed and went back to factory original for the time being. However the issue now is I have 12v to both fogs even with stalk switch off and car not running. I have to pull fuse to shut off. I am thinking once the SS3 pod shorted it was enough to stick the relay closed before the fuse blew. Does anyone know where the dedicated fog relay is on a 2020?
Fog lights wont turn off
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I bit the bullet and got 2 days on TIS. After more research on TIS is appears the fog and tail relays are internal to the main body ECU (pretty sure). All the troubleshooting recommendations in TIS are related to checking resistance and voltage at the plug pins on the ECU when fogs fail to illuminate. My issue is they are constantly on which tells me the internal relay has failed or multiplexer logic has been corrupted. Ill try resetting by liting battery terminals, but I sense a new ECU may be the only fix. i will be very disappointed if the DD SS3 fogs caused this as this was the only change I made to the fog circuit.
Any thoughts appreciated
I bit the bullet and got 2 days on TIS. After more research on TIS is appears the fog and tail relays are internal to the main body ECU (pretty sure). All the troubleshooting recommendations in TIS are related to checking resistance and voltage at the plug pins on the ECU when fogs fail to illuminate. My issue is they are constantly on which tells me the internal relay has failed or multiplexer logic has been corrupted. Ill try resetting by liting battery terminals, but I sense a new ECU may be the only fix. i will be very disappointed if the DD SS3 fogs caused this as this was the only change I made to the fog circuit.
Any thoughts appreciated
On many Toyota vehicles, the relay is in the "Junction Box" which is really the electronics behind the under dash fuse panel. I don't have the diagram for the 4Runner fog lights, so I don't know for sure.
The main body ECU controls most things, lights included, by grounding the negative side of the relay, light, etc. If 12 volts is applied to the main body ECU, such as a short, it will damage the main body ECU, sorry to say.
Since you are able to use TIS, look up the wiring diagram for the fog lights on your vehicle. That will help you sort out the problem.
Thanks. I have the 2020 wiring diagrams and they are great for troubleshoot, but the actual location of the fog relay on the truck stumped me. I had to dig around to summize its internal to the ECU. If the pins on the 2M and MB plugs on ECU were bad then light would not go on. Looks like I live without factory fog circuit or just wire them to the SPod myself. Or new ECU.
I would expect the fog & headlamp relays to be in the under hood fuse / relay box. Could be as simple as a stuck / bad relay, so best to try that first. Maybe tap on the relays with the handle of a screwdriver, with lights on in “off position” to see if that helps unstick it. If you do them individually, it would help isolate the specific relay and you could replace it. Just a thought.
Centrifugal
Member
[MENTION=609789]fkheath[/MENTION] seems to have the correct location for the Fog relay. You’ll have to take off that driver side kick panel and maybe the lower dash panel to access it.
Let us know how you make out.
Thanks. I tried messing with relays in the engine bay fuse box, until I discovered that the fog relay appears to be internal to the Main body ECU. Unless its a CAN communication issue, but I doubt its a software issue. if it was I would have to spring for a new ECU anyway, unless dealer can reprogram it.
Captain Spalding
Member
You have a 2020 wiring diagram? In PDF form? Where did you get it?
I find it odd that there’s not a separate relay for the fogs..
ETA I guess the fog relay is part of the ECU. It is in the 2010 diagram anyway.
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I got the 2020 wiring diagram from TIS website. I was also surprised and disappointed that the there was no dedicated fog relay that could be easily replaced. It appears its inside the ECU. So instead of replacing a $10 relay I have to replace a $700 ECU (unless there is a way to rest/reprogram it. I dont know)
Captain Spalding
Member
Man I hear this kind of thing way too often. If I ever add anything electrical to my 4Runner I’m going all new from the battery to the bulb.
Saker
Senior Member
Hence a 12V Auxiliary Circuit with fuses and relays and their own switches!
You have to keep add-on separate from the OEM circuits when at all possible!
Yeah....I have 6 accessories wired to my spod except the fogs. These are the factory drop in replacements made by DD and draw < 2A. I contemplated making the fogs a seperate circuit but thought I was in the safe zone. Learned lesson the hard way. Only good news is DD is stepping up and replacing the shorted pod under warranty along with some extended connector plus so I can make a harness.
What I still wonder about is if there is a replaceable or re programmable relay inside the ECU instead of having to replace the ECU completely (if I ever want to go back to factor y stalk switch circut).
