Where is the reverse/backup switch on a P30 chassis?

[ClydesdaleKevin]

Sent: 11/8/2008

Anyone know where the backup switch/reverse switch for the backup lights are on a 77 P30 chassis with a 454?  The lights won't come on...no voltage at the supply wires.

I'm guessing its either on the column or at the transmission...any clues?

Thanks!

Kev

[rustyescott1]

Sent: 11/8/2008

it's on the column

Rusty Escott

[tiinytina]

Sent: 11/9/2008

Kev,

   Its on the front side of the column facing the front of the rig. Mine is very near the top of the column. Also check your fuses of course! :-)

Tina

[ClydesdaleKevin]

Sent: 11/10/2008

OKAY...I've heard bottom of the column as a part of the neutral safety switch, which STILL works (it won't start in anything but start or neutral), and now I've heard near the top of the column...fuses are all good...

Which is it and where?

Anyone got any pictures?

Thanks!

Kev

[tiinytina]

Sent: 11/14/2008

Kev,

   My mechanic said some 454's have the switch on the tranny if you don't find one on the column.... dont' know if thats a help or not....

tina

[ontheroadagain]

Sent: 11/15/2008

It has 4 wires 2 for the back-up lights and 2 for the nuetral switch.  There are 2 switches inside.  One can go bad and the other will work fine.  Also, sometimes its just a little out of adjustment.  Have someone move the lever around while you watch the lights to see if they come on.   

[Slantsixness]

Sent: 11/17/2008 12:28 PM

Reverse lights, unlike the neutral safety porition of the switch are "live control" meaning that excessive current draw or poor grounding connections at the lights themselves will cause this switch to burn out. it's not unusual at all to have the neutral safey switch function perfectly, but the reverse light portion can be burnt slam up.

Remove the reverse light wires. connect the two wires together. did the reverse lights come on? Yes? the switch is bad. No? then your problem is not the neutral safety switch as pictured above. Ignition must be "on" for the reverse lights to work.
You can check the switch with an ohmmeter while the ignition is off, but the wiring must be disconnected (or you'll read the resistance of the light circuit!) when in Reverse, the pins should read shorted, or 0 ohms. if the lights are connected, it will still read less than 100 ohms, (the beeper on a fluke meter will still indicate this as a short, so watch out! it'll get ya all screwed up!!).

If, by chance, you are using additional reverse lights over the standard 2 bulbs, or you use the halon or halogen reverse lights that are brighter, then that may be too much current for the switch, and you should probably use a relay for the reverse lights if that's the case.

If the rear tail lights are wired incorrectly, the reverse lights can inadvertently become the "ground" for the tail lights. Just as is the same for the headlights grounding through the marker lights, which will screw up the turn signal operation. A quick way to see this is at night... remove the lenses, turn on the park lamps... does the reverse light(s) glow very dimly? then you definitely have a ground issue!
Another quick test is if the park lamps come on dimly when in reverse, but only when the parking lights are off.
This may be complicated greatly since you're using the LED replacement lamps. Try the old incandescent lamps... if everything works, then you definitely have a grounding issue, or the lights are mis-wired.

Lastly, in addition to the switch shown above, there is another connector at the floor that the reverse light circuit goes to, and an extension harness near the Rear axle. A bad, loose or corroded connection there will also keep the lights from coming on.

ok... basically Kev... I can fix it in about 10 minutes... so if you don't need them... wait until you get back to FL (that's this week?) and we'll fix 'em.

Tom

[DanielTBolger]

The neutral safety position is on the shift collar, light green and dark green wire at front side of the column facing the front of the RV.  If it's a standard transmission,  it's on top of the tranny.
I've built a lot of Chevy and GMC trucks for my brother's tow company.