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Old 12-26-2018, 05:54 PM   #1
76C10Stepside
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89 S10 Backup Lights Dead (how to remove NS/BU switch)

Both backup lights suddenly stopped working on my '89 S10 4.3/auto. They were both working.

Checked the left backup light. The bulb tested good, but no power to the socket. The socket is in great shape, all contacts very clean.

The neutral safety switch and backup light switch are in one plastic unit mounted to the steering column. It's whitish plastic like the dimmer switch, which is also on the column and which went bad a couple of years ago. The neutral safety switch portion of this unit works.

According to the wiring diagram, the backup lights share a fuse with the rear turn signals. The rear turn signals work great, so that rules out the fuse.

All the other lights work great and I doubt it's a grounding issue.

The Haynes manual has one picture of the neutral safety/backup light switch. The manual says to "remove the two mounting bolts". But there is NO MOUNTING HARDWARE on this switch. It's attached to the steering column with two plastic ears that fit into slots in the column jacket. Cannot figure out how to remove the switch short of breaking it off, and can't do that (truck would not start).

Wanted to try adjusting the switch. Manual says, "Insert a 5/64-inch diameter guage pin 3/8-inch into the guage hole on the new switch (see illustration)", but the illustration does not show the guage hole or mounting hardware! The switch is way up on top of the column, can't see much of it from any angle.

Tried putting the trans in every gear position to see if it was an adjustment issue (doubt it), die not get any backup lights in any position. Found that the outer part of the switch moves (has "detents") and can be moved manually. Tried moving it three clicks to the right to no effect.

Either no power is getting to the backup light switch (doubtful), or the backup light switch portion is bad (probable).

Tried to test for power to the switch, but can't even see where the plug for the backup lights is on the switch, and can't find it by feel.

Does anyone know how to remove this particular switch?
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Old 12-27-2018, 08:25 AM   #2
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

I'd like to know, also. I have an 85 and the switch was out of adjustment. Normally you would loosen the screws and move it, but there are none. I was able to push the switch over by hand, and it seemed to adjust it. All I can figure out is these are some kind of self-adjusting switch, but can't find anything on removing it.
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Old 12-27-2018, 03:45 PM   #3
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

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Originally Posted by Katrina/10 View Post
I'd like to know, also. I have an 85 and the switch was out of adjustment. Normally you would loosen the screws and move it, but there are none. I was able to push the switch over by hand, and it seemed to adjust it. All I can figure out is these are some kind of self-adjusting switch, but can't find anything on removing it.
If no answers here, I will go to a local auto parts store and take a look at a new one and let you know what I find out.

Pretty sure that in my case the switch is bad, but will test it once I am able to get it off the car.
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Old 12-27-2018, 04:09 PM   #4
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

Good idea! There's not a lot of activity here.
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Old 12-28-2018, 10:39 AM   #5
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

At the NSS/BUS, you can jump the light green wire and the dark blue wire. Then turn the key on. See if your BU lights work. If they work, you know your switch is bad.

Those switches do go bad. I've replaced quite a few over the years.
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Old 12-28-2018, 05:57 PM   #6
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

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At the NSS/BUS, you can jump the light green wire and the dark blue wire. Then turn the key on. See if your BU lights work. If they work, you know your switch is bad.

Those switches do go bad. I've replaced quite a few over the years.
Good info, thanks!

I need to remove the NSS/BU switch first b/c I can't even reach the plugs with it mounted on the column.

Do you know how to detach the NSS/BU switch from the steering column?
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Old 12-28-2018, 06:43 PM   #7
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

Somebody goofed when they wrote the Haynes manual, as the R&R it describes is obviously for the dimmer switch. I also have a Chilton's manual for this truck, and found that it has the correct info on how to remove this switch (section 6, chassis electrical, page 208, for anyone that has this book).

The description in the Chilton's is what I expected. It says to use a small pry bar to expand the backup switch-to-steering column retainers and remove the switch from the steering column. See part photo below.

Note that it does NOT say which bits on the switch are the "backup switch-to-steering column retainers". There are 5 pieces that go into the column, including the switch "blade" (the yellow plastic piece). Looks like the parts to pry open are on the BACK side of the switch, the ones that are closer together, and NOT the two at the front of the switch. Looks like it's going to be difficult to get to these, and will probably require using a small screwdriver. I have a very small pry bar, but doubt it will fit.

I will buy a new one first, and report back when I get it fixed.

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Old 12-31-2018, 06:47 PM   #8
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

PROBLEM SOLVED! In my case, it was the backup light switch that was bad.

I first removed the switch. To remove it, I used a 6-inch prybar to spread each of the ears on the cam on the BACK of the switch. Note that there is a bit of space under each ear inward from the part that snaps into the steering column. That's where you have to get the prybar. You have to do it from the back/downward side of the switch. There was just barely enough room to get in there, but it was not hard to do.

Once off, I pulled the backup light plug off far enough to get my multimeter probes in. With ignition on and trans in Reverse gear, I had power TO the switch, but no current through it. I then plugged the new switch in and tested the lights with the switch non installed, and they worked, so all I had left was to snap the switch into the column. That was not hard either.
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Old 01-02-2019, 01:01 PM   #9
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

I'm glad you figured it out. I could find no information on how to remove that switch. Seems like it would difficult to get it out, considering where it is and what you have to do. Good picture of it, I may buy a switch just to have on hand so I can see how to get the old one out.
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Old 01-02-2019, 05:27 PM   #10
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

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Originally Posted by Katrina/10 View Post
I'm glad you figured it out. I could find no information on how to remove that switch. Seems like it would difficult to get it out, considering where it is and what you have to do. Good picture of it, I may buy a switch just to have on hand so I can see how to get the old one out.
Yeah, it's good to have backup lights again, necessary where I live. If/when you replace your switch, you will find it an easy job. In the attached photo, I've circled in red the two ears you have to pry outward/upward to remove the switch. I was able to remove the switch, then unplug the two plugs (mine does not use the lone spade connector on the right side of the new switch, no idea what it is for).
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Old 01-02-2019, 05:35 PM   #11
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

Thanks, I see that better now. Do you have to pry the tabs away from each other to remove the switch? And they are on the lower side, closer to the floor, right?
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Old 01-02-2019, 09:01 PM   #12
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

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Thanks, I see that better now. Do you have to pry the tabs away from each other to remove the switch? And they are on the lower side, closer to the floor, right?
No, I pried up the right side first, then the left side, which worked fine. They don't need to be pried very far, just enough to clear the slot in the steering column. I had to pry up both sides (would not come off after getting one side off).

Yes, the cam with the tabs is closer to the floor, so you have to do it by FEEL. You can feel the raised part where the corner of the pry bar will need to go (can't fit the whole thing, just a corner of it). My pry bar is a tiny version of a flat style crowbar. If you have a set of plastic pry bars (like for removing door panels and such), one of those will probably work.
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Old 01-05-2019, 08:12 AM   #13
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

I'm sure glad you figured out how to do this. I wish there was more activity in this area of the forum.
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Old 01-05-2019, 09:29 PM   #14
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Re: 89 S10 Backup Lights Dead (how to remove NS/BU switch)

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I'm sure glad you figured out how to do this. I wish there was more activity in this area of the forum.
Me too! The S10 forum seems to get even less traffic.
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