Tracing wires and adding Follow me home in a car

Thread Starter

Ping pong

Joined Feb 13, 2022
29
Currently I am working on a small project that'll help retrofit follow me home feature on my car. This requires me to tap into a few specific wires of the headlight switch (one on the steering wheel). However the connector, as expected, has about 6-8 wires running through it. The wires are of high beam, low beam, turn signals, the parking lights and some other (probably ground and live too). I want to find out which of these belong to the parking lights so that I can tap into them, however, I don't understand how I'll do it using a multimeter.
I recently bought the multimeter and am still trying to understand how to use it in different situations.
 

bassbindevil

Joined Jan 23, 2014
497
Maybe you can stick a thin probe (like a bare solid wire) down beside each wire going into the connector and measure the voltage with respect to chassis ground. Or, stick a fine sewing needle through the insulation of each wire until it touches the conductor.
 

Jon Chandler

Joined Jun 12, 2008
292
That's not confusing! It's even in color!

There are different sections for different models. Print out (in color) the diagrams for your model, tape them together, and it should be pretty simple to figure out what goes where.

I rebuilt a melted wiring harness on a 1976 GMC Motorhome. That was a challenge. I had a copy of a copy of a black and white diagram that had originally been printed on one 16' long page. The color of a wire might be marked on each end, but not on the five pages in the middle, which didn't line up exactly being copies and copies.

One suggestion is to figure out which each fuse goes. Pull ALL the fuses and measure continuity between the fuse terminal and where you think the wire goes.
 

Thread Starter

Ping pong

Joined Feb 13, 2022
29
That's not confusing! It's even in color!

There are different sections for different models. Print out (in color) the diagrams for your model, tape them together, and it should be pretty simple to figure out what goes where.

I rebuilt a melted wiring harness on a 1976 GMC Motorhome. That was a challenge. I had a copy of a copy of a black and white diagram that had originally been printed on one 16' long page. The color of a wire might be marked on each end, but not on the five pages in the middle, which didn't line up exactly being copies and copies.

One suggestion is to figure out which each fuse goes. Pull ALL the fuses and measure continuity between the fuse terminal and where you think the wire goes.
Tbh I'm an accounting student and all this is completely new to me, hence why I couldn't understand the diagrams. However the idea of checking continuity makes sense. The parking lights trigger a relay. I could test continuity from that.
 

MisterBill2

Joined Jan 23, 2018
12,690
Currently I am working on a small project that'll help retrofit follow me home feature on my car. This requires me to tap into a few specific wires of the headlight switch (one on the steering wheel). However the connector, as expected, has about 6-8 wires running through it. The wires are of high beam, low beam, turn signals, the parking lights and some other (probably ground and live too). I want to find out which of these belong to the parking lights so that I can tap into them, however, I don't understand how I'll do it using a multimeter.
I recently bought the multimeter and am still trying to understand how to use it in different situations.
What is "follow me home" feature?? And what signals does it need? If the witch on the steering wheel ties to the body control computer then the signal on the wire will not be anything like an actual power feed.
So if you are installing some accessory we will need to know what inputs it needs, and what outputs it has. My experience is that the switches on the steering wheel, especially, are logic level to the BCC (body control computer) and not useful for much else.
As for poking holes in the insulation of the wires, that is a VERY POOR CHOICE because damaged insulation never becomes non-damaged insulation. So the conductors corrode and then stop conducting.
 

Jon Chandler

Joined Jun 12, 2008
292
That is about the simplest, easiest to follow wiring diagram ever. Take a few minutes to figure it out. It will be far easier than trying to beep things out.
 

Thread Starter

Ping pong

Joined Feb 13, 2022
29
Alro
That is about the simplest, easiest to follow wiring diagram ever. Take a few minutes to figure it out. It will be far easier than trying to beep things out.
Okay, so I looked into it and you're right, it's pretty straight forward. Although there is one thing that I don't understand, there are two diagrams for each component. One labeled 'TMC made' and other 'Except TMC made'. Both have similar circuits but different wire colors.
What is the meaning of these two
 

MisterBill2

Joined Jan 23, 2018
12,690
These drawings are partial maps of portions of systems. The challenging part will be discovering which map of the connector cavity drawings matches the connector that you are looking at. So it will take a lot of looking.
 

Tonyr1084

Joined Sep 24, 2015
6,954
owners manual has probably been recycled into a sci-fi novel by now and the wiring diagrams online are too confusing.
Keep in mind the TS is an accountant student. This is as foreign to him (assumed male) as brain surgery is to the rest of us.
Tbh I'm an accounting student and all this is completely new to me
What is "follow me home" feature?
Wondering the same thing.
That is about the simplest, easiest to follow wiring diagram ever. Take a few minutes to figure it out.
Again, easy for those who speak the language.

I was going to suggest you contact your local dealership service department and ask them for a print-out of that plug. I've done that in the past with several different vehicles. Dealerships I've dealt with seem ready to help you understand your electrical wiring. But if this is like a foreign language to you then since you're a student I'm going to assume there may also be some sort of auto shop program that might be able to help you with the physical "hands on" of your project.

Use of a multimeter is great if you understand what you're looking at. I have a neighbor who frequently has a dead car battery. He calls me and asks me to check his battery. One year for Christmas I gave him a simple meter. He had no idea how to use it. So he set it to current and then checked the battery voltage. POOF! went the fuse in the meter. Those who don't know how to use a tool should gain further instruction on its use and functions. Again, the auto shop will likely be your best place to begin learning about electronics and electrical wiring as well as wiring diagrams and how to read them.

Good luck with your project. Though I, too, am wondering about "Follow Me Home".
 

Tonyr1084

Joined Sep 24, 2015
6,954
Been scrolling through the wiring diagram for your Toyota Motor Car (TMC). It's not so straight forward as one might expect. Perhaps a Chilton car manual might have clearer wiring diagrams. What I saw had multiple multiple multiple system specific diagrams. Knowing what you're looking for is the first hurtle. I looked for headlights and for multi-function switches. No, I didn't get through the entire thing, I got as far as the M's before I gave up. To someone unaccustomed to this sort of diagram it's got to be overwhelming. Maybe I'll scroll further down and see if there's a "Parking Light" section, but I think I saw something in the "Headlights" section.

Ping pong don't be discouraged. We'll figure a way to get you to where you're trying to go.
 

Tonyr1084

Joined Sep 24, 2015
6,954
I you guys Google broke? https://gomechanic.in/blog/follow-me-home-headlights/

That said the TS probably won't be able to activate something NOT built/programed into his car.
Generally speaking I don't google everything I read. But it's a good habit to get into.

This is what I read (overall)
  • The headlights stay on for 10-15 seconds to provide a lit track or path for you.
Both my vehicles have that feature. Thanks @shortbus that explains a lot.

So the TS wants headlights to remain on for a period of time after shutting the vehicle off. As I said, mine have that feature built in. My wife's car - 2009 Toyota Venza - she hates it. So in the setup we set it up to NOT keep the lights on for about 30 seconds I think is about the time period my vehicles do the FMH thing. On my truck I've tried to disable that feature but have been unsuccessful.

So the TS basically wants to push a button and power the headlights for some as yet unspecified period of time. That's doable. If your 2010 Corola probably has that feature already in its "Setup" menu. My wife's 09 has it. Don't see why your 10 doesn't. That's the first place to look, if your car has the FMH programming already built in. If it's not there then we can come up with a work-around. Believe me, it's easy. And quite possibly "Plug N Play" components already built for timing functions that can do just what you ask. There will likely be a few more components involved, but again, we can walk you through it - if necessary.
 

Thread Starter

Ping pong

Joined Feb 13, 2022
29
Keep in mind the TS is an accountant student. This is as foreign to him (assumed male) as brain surgery is to the rest of us.
Well, thank you for understanding! I have done a few small projects like this in the past. However, this might be kinda the most demanding of them all. However, I already have a game plan in mind.
 
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