Electrical horror show
#21
05-07-2018, 07:26 AM
I've been following a while now.
What makes me wonder if somebody has been tinkering with the wiring before.
It sounds as it comes down to check all wiring.
If the backup lights are on all the time if should be possible to figure from connector to connector backwards or forward where that current comes from.
What makes me wonder if somebody has been tinkering with the wiring before.
It sounds as it comes down to check all wiring.
If the backup lights are on all the time if should be possible to figure from connector to connector backwards or forward where that current comes from.
#22
05-07-2018, 10:30 AM
No disrespect to the many that are trying to help the OP, that is after all the point of this community.
The likelyhood of all of these problems arriving at the same time and having no relation to each other is very low. Statistically the simplist explanation is the most likely until its ruled out (or fixes the problem). There may be more than one root cause and if so we can address BCM modules, crappy grounds, etc next. In the meantime, the back up light circuit is the original complaint, possibly the scene of the crime and a simple circuit so this problem needs to be solved first.
If this were my truck this is what I would do:
Locate the G404 ground that you have on your diagram from the other post. Disconnect it and see if the back up lights go out as they should. If they dont then there is a ground problem in this circuit at a minimum and/or the moderator is right, the wiring has been tampered with. If this is the case, report back.
If the lights go out, reconnect and then pull the Veh B/U fuse in your diagram. If the lights are still on find the lt green wire just as it leaves the fuse block and probe it with a pin or needle probe to see if there is 12V on this wire. If there is then 12V is shorted to one of the 4 legs which radiate from the S309 splice and ultimately feed the back up lights (which should be dead after the fuse is pulled). If there is not then report back.
If this wire is still hot then you need to find the source of the 12V on those 4 wire legs. This wire leaves the fuse block going to the back up lights but passes through the S309 splice on the way, creating 4 lt green wire legs. One of these legs is hot when it shouldnt be with the fuse pulled so we have to figure out which one it is. Before you cut any wires follow this harness back from the back up lights through the S309 splice towards the fuse block and look for any obvious problems first. If you find yourself here then report back so we can finish finding this part of your problem.
Intermittent and/or strange electrical problems can feel like black magic or the universe being out to get you but these problems are always solvable. Sometimes you get lucky and find it early, other times its more like an easter egg hunt but analysing the circuit first and coming up with a few "if then else conditional branches" helps narrow down your search. IOW, if I pull the last fuse that allows power on this circuit and the load is still energized, then there is an improper source of 12V on this circuit after the fuse towards ground. If pulling the fuse turns off the lights then the problem is back towards the battery and its something else. Some people like to look at grounds first or work from the load back or work from power towards the load. Do whatever suits the way your brain works. I like to look at the circuit and look for the test that rules half of the options out and then rinse and repeat. I just had to do this with a Toyota with an electric cooling fan problem. The fault was a partially broken wire in a cable bundle between the fuse block and the fan all nice and wrapped up inside the cable. It took a while but there it was as I ruled out everything else step by step. The only thing left at one point was a break in the wire between splice XYZ and the load so I started splitting the wrap and there it was, underneath out of view up against and piece of metal. I understand the urge to go straight to a common problem area and doing a few of those can get a quick fix but once exhausted then the real work starts. Hell even I will do plugs wires and cap on a misfire if the vehicle is overdue because we are going there anyway but if that doesnt fix it then on to a proper diagnostic route.
Good luck.
George
The likelyhood of all of these problems arriving at the same time and having no relation to each other is very low. Statistically the simplist explanation is the most likely until its ruled out (or fixes the problem). There may be more than one root cause and if so we can address BCM modules, crappy grounds, etc next. In the meantime, the back up light circuit is the original complaint, possibly the scene of the crime and a simple circuit so this problem needs to be solved first.
If this were my truck this is what I would do:
Locate the G404 ground that you have on your diagram from the other post. Disconnect it and see if the back up lights go out as they should. If they dont then there is a ground problem in this circuit at a minimum and/or the moderator is right, the wiring has been tampered with. If this is the case, report back.
If the lights go out, reconnect and then pull the Veh B/U fuse in your diagram. If the lights are still on find the lt green wire just as it leaves the fuse block and probe it with a pin or needle probe to see if there is 12V on this wire. If there is then 12V is shorted to one of the 4 legs which radiate from the S309 splice and ultimately feed the back up lights (which should be dead after the fuse is pulled). If there is not then report back.
If this wire is still hot then you need to find the source of the 12V on those 4 wire legs. This wire leaves the fuse block going to the back up lights but passes through the S309 splice on the way, creating 4 lt green wire legs. One of these legs is hot when it shouldnt be with the fuse pulled so we have to figure out which one it is. Before you cut any wires follow this harness back from the back up lights through the S309 splice towards the fuse block and look for any obvious problems first. If you find yourself here then report back so we can finish finding this part of your problem.
Intermittent and/or strange electrical problems can feel like black magic or the universe being out to get you but these problems are always solvable. Sometimes you get lucky and find it early, other times its more like an easter egg hunt but analysing the circuit first and coming up with a few "if then else conditional branches" helps narrow down your search. IOW, if I pull the last fuse that allows power on this circuit and the load is still energized, then there is an improper source of 12V on this circuit after the fuse towards ground. If pulling the fuse turns off the lights then the problem is back towards the battery and its something else. Some people like to look at grounds first or work from the load back or work from power towards the load. Do whatever suits the way your brain works. I like to look at the circuit and look for the test that rules half of the options out and then rinse and repeat. I just had to do this with a Toyota with an electric cooling fan problem. The fault was a partially broken wire in a cable bundle between the fuse block and the fan all nice and wrapped up inside the cable. It took a while but there it was as I ruled out everything else step by step. The only thing left at one point was a break in the wire between splice XYZ and the load so I started splitting the wrap and there it was, underneath out of view up against and piece of metal. I understand the urge to go straight to a common problem area and doing a few of those can get a quick fix but once exhausted then the real work starts. Hell even I will do plugs wires and cap on a misfire if the vehicle is overdue because we are going there anyway but if that doesnt fix it then on to a proper diagnostic route.
Good luck.
George
Last edited by GeorgeLG; 05-08-2018 at 10:35 PM.
#23
05-07-2018, 12:00 PM
Hey George, hope my comments aren't being taken as offensive. No offense taken by me at all as one of the "posters" 
. I have no problem being found wrong in the course of helping the OP. I've been wrong before and I'll be wrong again. I look at these forums as us all standing under the hood discussing strategies for the best direction to go. Personally I'm just as happy for an OP finding the problem whether my comments help or not. I know what it's like to be frustrated by these things, especially if it's your daily driver.
Cheers!
. I have no problem being found wrong in the course of helping the OP. I've been wrong before and I'll be wrong again. I look at these forums as us all standing under the hood discussing strategies for the best direction to go. Personally I'm just as happy for an OP finding the problem whether my comments help or not. I know what it's like to be frustrated by these things, especially if it's your daily driver. Cheers!
#25
05-07-2018, 03:23 PM
Luckily I have my corolla which is my usual daily. However, it sucks not having the blazer when we have to go grocery shopping or I need to go somewhere with the dogs. I don't think I'll get a chance to look at it today since it is supposed to rain for the 4th straight day.
#26
05-07-2018, 07:10 PM
So, it didn't rain, but I didn't make much progress either. I hooked the battery up and the car wouldn't start, it blew the 10a gauges fuse. I put a new fuse in and it started and ran fine. about five minutes later my tailgate glass release popped, the back up lights came on, and my amp turned on. The amp turn on I think has been on the last couple of times the back up lights came on. I pulled the power cable to the amp and unplugged the tail lights. I plugged them back in and they stayed off. I have the back hatch window unplugged for now. I pulled some of the covers back around the tail light wiring on the driver's side and at all looks good. I can't really tell without pulling out and removing the tape from several feet of wiring. However, where the wire runs under the carpet and goes forward it is very wet. That as far as I got today.
Last edited by Tajohns34; 05-07-2018 at 07:13 PM.
#27
05-07-2018, 10:36 PM
So:
The truck would not start until the gauge fuse was replaced?
Is the tail light problem the same as the back up light problem or are there two different issues here?
Where did you unplug the lights?
The wiring cable that passes under the carpet is sitting in water?
George
The truck would not start until the gauge fuse was replaced?
Is the tail light problem the same as the back up light problem or are there two different issues here?
Where did you unplug the lights?
The wiring cable that passes under the carpet is sitting in water?
George
#28
05-08-2018, 04:51 AM
This is going to be kinda offtopic, but the weeks I've spend reading BF learned me a respect to GeorgeLG and rockp2. They are pros in their ways. rockp2 has a huge experience coming from a real case study, while GeorgeLG is an analytic expert. Two different attitudes that sometimes clash together... 
#29
05-08-2018, 08:16 AM
That's how you get the best work done. People with different viewpoints sharing ideas and building on each other. I have been thinking about what rock2p said since yesterday , trying to see if his ideas can help find the answer for the OP.
George
George
#30
05-08-2018, 11:31 AM
The truck would not start until the gauge fuse was replaced?
Yes
Is the tail light problem the same as the back up light problem or are there two different issues here?
I should clarify this. I removed the passenger side bulb to help from draining the battery. To turn the lights off I disconnected the entire tail light harness.
Where did you unplug the lights?
The harness right at the driver's side tail light.
The wiring cable that passes under the carpet is sitting in water?
It isn't submerged but it is wet. I can't get the carpet up because all of my floor anchors are stuck in, the nuts under the car have rusted off of the welds. I might just cut the carpet around them to get it out.
Yes
Is the tail light problem the same as the back up light problem or are there two different issues here?
I should clarify this. I removed the passenger side bulb to help from draining the battery. To turn the lights off I disconnected the entire tail light harness.
Where did you unplug the lights?
The harness right at the driver's side tail light.
The wiring cable that passes under the carpet is sitting in water?
It isn't submerged but it is wet. I can't get the carpet up because all of my floor anchors are stuck in, the nuts under the car have rusted off of the welds. I might just cut the carpet around them to get it out.