Fuse 24 keep blowing
01-23-2011, 01:21 AM
#1
Drifting
Thread Starter
Fuse 24 keep blowing
87 S4..... I have been through all the threads I can in troubleshooting this. Interior lights and rear hatch do not operate. When I got the car these did not work so I replaced the fuse and got them to operate fine. Fuse was 25a and it is only suppose to have 7.5a. After replacing the rear hatch shocks they quite working again and it pops the fuse on inserting. No contact is being made with the roof metal from the interior lights. I have been through most of the wiring and interior light switches and I do not see any burned or melted wires. I have the CE panel out for contact cleaning. I found some dirty connections and cleaned them. I have one lead related to the rear hatch shocks that I want to check as soon as I get the CE panel back in. A fellow rennlist traced his short to the wiring going to the back hatch wires being stretched from opening and closing(maybe the new struts caused a short? I have disconnected all the power wires to the interior lights and the rear hatch and it still pops fuses. I did not disconnect the red door lights as I did not have enough wire to unplug, same thing with the door pin switch. It is kind of hard to exclude them when you can not disconnect them. I have not disconected the brown ground wires to the interior lights. Will that make a difference? I understand they come on with ground, but without the power wire I would not think they would pop the fuse.
01-23-2011, 01:36 AM
#2
Rennlist Member
Rennlist Site Sponsor
While there are many possible problems, the most common one is that the power wire to the light above the rear view mirror shorts to the body.
If you are handy with electrical work, you can make a tool to help you find the problem.
Get a small 12 volt bulb, such as an instrument light bulb. Get three feet of "zip cord" or "lamp cord" at Home Depot or Lowe's. This is the brown or ivory two-conductor wire used to connect a lamp to the wall socket.
On one end of the lamp cord, solder one conductor to the center of the bulb connection, and the other connector to the metal base of the bulb.
Get one of your many blown fuses. On the face of the fuse (where the numbers are), there are two little metal bits. Scrape the plastic away until you can get to the metal bits. On the other end of the lamp cord, solder one conductor to each of the little metal bits. Make SURE that you don't short the metal bits with a blob of solder or wire strands!
Plug the blown fuse with the bulb attached into the connector for Fuse #24. If there is a short circuit, or if the interior lights are on, the bulb will glow. With the doors and hatch closed, start checking the wires for shorts to ground - when you remove the short, the bulb will go off.
If you are handy with electrical work, you can make a tool to help you find the problem.
Get a small 12 volt bulb, such as an instrument light bulb. Get three feet of "zip cord" or "lamp cord" at Home Depot or Lowe's. This is the brown or ivory two-conductor wire used to connect a lamp to the wall socket.
On one end of the lamp cord, solder one conductor to the center of the bulb connection, and the other connector to the metal base of the bulb.
Get one of your many blown fuses. On the face of the fuse (where the numbers are), there are two little metal bits. Scrape the plastic away until you can get to the metal bits. On the other end of the lamp cord, solder one conductor to each of the little metal bits. Make SURE that you don't short the metal bits with a blob of solder or wire strands!
Plug the blown fuse with the bulb attached into the connector for Fuse #24. If there is a short circuit, or if the interior lights are on, the bulb will glow. With the doors and hatch closed, start checking the wires for shorts to ground - when you remove the short, the bulb will go off.
01-23-2011, 02:10 AM
#4
Team Owner
Disconnect the battery, Then from your post you might try removing the trims for the hatch,
first take off the sun visors then the upper hatch light then remove the trim behind the visors (5 push in clips) hold it in place.
Then remove both sides of the hatch side trims (push to the center of the car and they will come loose)
NOTE be careful with the defroster leads as you can shear them off.
Pay attention to the wires as they transition from the roof section to the hatch look for cut or damaged wire.
Also look along the edges of the hatch where the small trims are , the metal clips can cut the wires and cause the lights to short out.
Also get some heatshink and cover every lead to every light in the car,
this includes both of the grounding wires for each lamp.
Next would be if you have worked on the rear big speakers , the securing screws pass very close to the rear wire harness and can short the harness ( this is in reference to the RR big speaker.
Also remove the screws for the right side of the roof liner and the right sun visor,
and pull it down look for melted wires or chafing wires contacting the roof metal.
Next would be to remove both of the door panels and inspect the wire sheath for damaged wires where they come out of the tube.
Look at the CE panel and see if the rear harness has any melted wires going to the rear harness connector ,
remove the right side amp cover, and lift the carpet , inspect the harness for damage, the harness runs along the floor and then up the B pillar,
There is a connector behind the right Big speaker where the harness splits into 2 directions one for the mirror light / interior light ,
and then to the rear for the hatch
first take off the sun visors then the upper hatch light then remove the trim behind the visors (5 push in clips) hold it in place.
Then remove both sides of the hatch side trims (push to the center of the car and they will come loose)
NOTE be careful with the defroster leads as you can shear them off.
Pay attention to the wires as they transition from the roof section to the hatch look for cut or damaged wire.
Also look along the edges of the hatch where the small trims are , the metal clips can cut the wires and cause the lights to short out.
Also get some heatshink and cover every lead to every light in the car,
this includes both of the grounding wires for each lamp.
Next would be if you have worked on the rear big speakers , the securing screws pass very close to the rear wire harness and can short the harness ( this is in reference to the RR big speaker.
Also remove the screws for the right side of the roof liner and the right sun visor,
and pull it down look for melted wires or chafing wires contacting the roof metal.
Next would be to remove both of the door panels and inspect the wire sheath for damaged wires where they come out of the tube.
Look at the CE panel and see if the rear harness has any melted wires going to the rear harness connector ,
remove the right side amp cover, and lift the carpet , inspect the harness for damage, the harness runs along the floor and then up the B pillar,
There is a connector behind the right Big speaker where the harness splits into 2 directions one for the mirror light / interior light ,
and then to the rear for the hatch
01-23-2011, 01:35 PM
#5
Rennlist Member
Rennlist Site Sponsor
mrmerlin - could you be more specific?
Excellent reply! I can just imagine the awe and dismay felt by a rank novice when he gets more than he expected. Reminds me of the old joke about the little girl who was assigned to do a book report on a book titled "All About Elephants". Her report started, "This book told me more about elephants than I really wanted to know..."
Excellent reply! I can just imagine the awe and dismay felt by a rank novice when he gets more than he expected. Reminds me of the old joke about the little girl who was assigned to do a book report on a book titled "All About Elephants". Her report started, "This book told me more about elephants than I really wanted to know..."
01-23-2011, 01:52 PM
#6
Rennlist Member
Two ways to address door pins.
Its possible to unhook the harness from the support loops and create enough slack in the brown/white wires to enable removal of the pins. Then, you would use vicegrips with a jaw liner to clamp the wire from retracting into the hole after clipping off the door pin.
Alternately, you can clip the wire near the firewall. Tape a monfilament string or even a small wire to it. Remove the pin, and as the brown/white wire is removed it will pull the string or wire through the hole.
Do the cleaning, solder a new wire to the pin, and reverse the process. Then either solder or crimp the old stub wire to the new wire by the firewall on each side. Shame they weren't made with a simple plug connector. In fact, you could add that.
For the door end lights, mine have enough slack to service, yours might not, removing panel will provide access.
The door pins and door end lights are real important, lots of good things happen when they work.
Here's a pin getting its rehab:
Its possible to unhook the harness from the support loops and create enough slack in the brown/white wires to enable removal of the pins. Then, you would use vicegrips with a jaw liner to clamp the wire from retracting into the hole after clipping off the door pin.
Alternately, you can clip the wire near the firewall. Tape a monfilament string or even a small wire to it. Remove the pin, and as the brown/white wire is removed it will pull the string or wire through the hole.
Do the cleaning, solder a new wire to the pin, and reverse the process. Then either solder or crimp the old stub wire to the new wire by the firewall on each side. Shame they weren't made with a simple plug connector. In fact, you could add that.
For the door end lights, mine have enough slack to service, yours might not, removing panel will provide access.
The door pins and door end lights are real important, lots of good things happen when they work.
Here's a pin getting its rehab:
01-23-2011, 01:53 PM
#7
Team Owner
Wally did I leave something out?
I had to go through a few cars with a shorted roof harness and even had to replace one for a customer before installing new carpets.
My Green 86 also suffered the same fate a shorted roof harness
I had to go through a few cars with a shorted roof harness and even had to replace one for a customer before installing new carpets.
My Green 86 also suffered the same fate a shorted roof harness
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01-23-2011, 03:19 PM
#9
Drifting
Thread Starter
Thank you all for the excellent replies, one thing before I proceed further. I just put the CE panel back in. I got all the plastic block leads plugged in. I think anyway. The L and the R spots are empty. I hope I did not leave any wires behind the panel. I am fairly certain that I did not. Can anyone tell me for sure?
01-23-2011, 03:41 PM
#11
Drifting
Thread Starter
I did make sure I color coded everything and double checked all the letters. I just wish I would have paid closer attention to make sure those two spots were empty to begin with. I have reached back behind and can not feel any blocks left behind so I should be good. I am going back out to double check again.
01-23-2011, 05:23 PM
#12
Drifting
Thread Starter
I am at the point of removing the hatch trim and I do not have a clue. Visors are off, roof light out but I can not see the next step. Is there a certain direction it needs to go. I do not see any kind of tabs?
01-23-2011, 07:24 PM
#14
Drifting
Thread Starter
Thank you Allan, I did make some progress today. I am not sure what I did but the fuse it not blowing at this moment. I did use the 12 v bulb set up to try to find the short. I never did get the rear hatch trim off but I shook all the wires I could to try to make the bulb go out. It never did. After a while I got curious and decided to burn up another fuse. To my surpise it did not blow. I know there is still a problem so here is where I am at. Both hatch releases are working, clock working. Interior lights working but they are not going out with the delay. I can hear the delay relay cycling after about 25 sec. so I believe it is working. What does not work is the glove box light and the passenger side red light. I tested both bulbs and they are good. I am guessing these might be on the same circuit and might be the root of all my trouble.
Last edited by rgs944; 01-23-2011 at 07:43 PM.
