I have a 99, 4dr, s-10 blazer with a 4.3l v6, and about 68,000 miles. I have no back-up lights. i checked the bulbs, fuses and any connections i could find with no luck. Then I checked the adjustment on the park reverse neutral switch mounted on the transmission, which was still ok. So, i picked up a new park reverse neutral switch and after installing it, not only were my back-up lights still not working but now when i put my car in drive the starter would engage. I'm guessing i got the wrong switch. i put the old one back in and now i'm trying to figure out what's going on. I installed the new switch with the trans in neutral and the markings lined up. so, it must of been the wrong switch, right? Also, my truck will not start in neutral, i thought it was supposed to, but that would indicated a problem with that switch as well. help please.

thank you.

 

Which switch did you replace? The unit on the tranny? The one behind the shift cable? I believe that controls your back up lights, brake lights, and the gear indicator on the dash. Did you notice that the hole is oblong to match the oblong pattern on the tranny shift rod? If you got it on wrong, I could see where the truck would think your in the wrong gear and back up lights wouldn't work, and neither would your nuetral start.

Yes, it should start in nuetral with your foot on the brake.

 

Yes I tried to replace the switch on the tranny. Thats the one that controls the reverse lights on an automatic transmission, right? I see what you're saying about the oblique shape of the opening on the switch, but i don't think there is any way i installed it wrong. I don't think the rotating part of the switch turns 180 degrees, and when i put it in the marking on the part that spins lined up with the markings on the body of the switch. But even if i did install it wrong, is there any position i could have put it in that would explain why putting my car in drive would engage the starter? Does anyone know where i can get another one of these switches? I returned the one i got from pet boys, and they say it was the right switch. I think either that switch was defective or their parts inventory computer is worng.

 

Your right, there is only one way to attach the switch. Just wanted to make sure you didn't force it.

Did you check the fuse? I think you mentioned it already.

After that, time for a volt meter, you need to find out if the power is getting back to the lights, and trace the wires into the cab to see if there is a short. There aren't too many parts involved here. Ask swart to post up a wiring diagram.

 

I'll get you a wiring diagram or two (if I can find them) when I get home from work today. Should be able to pull up something on the reverse light wiring.

 

LOL, so I lied... I just looked up this stuff on Alldatadiy.com for my 2000. I would think that everything should be the same on your '99.

The Park, Neutral, backup switch can be adjusted and I'm betting that it was just alittle out of adjustment is why it started in D.
To adjust the P/N/Backup switch:
[ul][*]Check the switch for proper operation. [*]The engine must be in the P (Park) or N (Neutral) positions only. If adjustment is required, loosen the switch retaining bolts and rotate the switch slightly. [*]Tighten the bolts and check the switch for proper operation. [*]Repeat the switch adjustment procedure until the engine starts when the shift lever is positioned in park and neutral. [*]If improper operation continues refer to Park/Neutral Position Switch Replacement.[/ul]

Just to throw this out there, you did check your fuses, right???

 

Yes, I checked the fuses first and connections. I'll try to adjust the switch again. Should i go by the markings on the switch, or just play with it until it works? Because right now, when the tranny is in neutral the arrow on the body of the switch matches up with the little line on the part of the switch that spins with the shaft on the trans. I thought that was how you knew it was adjusted properly. And to clarify, after I tried to install the new switch the car was starting itself when i put it in drive. All i had to do was put the key in and turn it to acc then put the car in drive, without touching anything else other than the brake and the shifter, and the car would start. And if i put the car in drive while the it was running i could hear the starter engage. I don't know why that was happening. I took that switch out right away and put the old one back in, i think the new switch must of been defective. I don't know how that could happen, even if i put it in completely wrong.
thank you for the wiring diagrams.