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DeltaBravo
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Joined: February 29, 2016
Posts: 179
Location: Long Beach, CA
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 Posted: Fri Feb 24, 2017 10:25 am Post subject: Rear reverse lights do not work. |
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Hello.
I wanted to share my thoughts before I start ordering a new reverse light switch. This is for a 1976 Manual Bus.
My rear reverse lights do not turn on when I put the manual gear lever into Reverse.
I have done the following:
1) Raised the rear of the Bus to allow the wheel to spin freely. This way I can put the gearbox into Reverse and allow the fluid inside to pressurize the switch.
2) Of course, I check to make sure I have the proper amount of gear oil, and I do.
3) With key on / Engine off- I checked for 12VDC at one terminal at the switch. I have 12.3 VDC.
4) The other terminal from the switch runs back into the engine compartment to the rear light assemblies. I disconnected the terminal from the switch. Then I disconnected the single connector before the light asseblies in the engine compartment and hooked that end onto a body ground. Went back underneath to the switch with my multi meter and checked for continuity. It reads good. So now I know the wire from the switch to the single connection is good.
5) Keeping the single connection in the engine compartment disconnected. I took the other end of that single connection and disconnected the terminals to the light assemblies and read continuity from the single spade connection to each spade at the taillight. They are both good (reading continuity).
So...in conclusion. I am getting 12vdc at the switch and all the wiring from the switch to the tail lights are good. Can I safely assume the switch is bad? Is there a way to check?
Also, while writing this I just realized I didn't check to make sure that wire isn't grounding out while connected...But I am assuming that would blow a fuse.
Thanks
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1976 Bus, 2.0 Hydraulic lifters, Manual.
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Tom Powell
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Joined: December 01, 2005
Posts: 4855
Location: Kaneohe
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| Posted: Fri Feb 24, 2017 10:51 am Post subject: Re: Rear reverse lights do not work. |
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| DeltaBravo wrote: |
| ... allow the fluid inside to pressurize the switch. ... I am getting 12vdc at the switch and all the wiring from the switch to the tail lights are good. Can I safely assume the switch is bad? Is there a way to check? ... |
I'm not familiar with the '76 wiring, but I would assume that the switch is mechanical and controlled by the shift linkage. You should be able to put a jumper wire across the switch and the lights will work. If not, this would indicate a bad switch. Perhaps the switch is good but the mechanical linkage to the switch is skeewopit. I'm also unsure when the circuit has power; ignition off/on, lights off/on.
Aloha
tp |
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DeltaBravo
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Location: Long Beach, CA
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aeromech
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Joined: January 24, 2006
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Location: San Diego, California
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| Posted: Fri Feb 24, 2017 12:25 pm Post subject: Re: Rear reverse lights do not work. |
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I replaced a bad switch a few months ago. It's a plunger and not pressure activated. Just pull off both wires and simply touch them togather. With the key ON the lights should illuminate. If they don't, check the inline fuse between the coil + and the plunger switch. If they still don't work check the light fixtures. Might be bad bulbs, corroded sockets, bad grounds, etc.
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DeltaBravo
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Joined: February 29, 2016
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Location: Long Beach, CA
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sjbartnik
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Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Fri Feb 24, 2017 1:32 pm Post subject: Re: Rear reverse lights do not work. |
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| DeltaBravo wrote: |
My rear reverse lights do not turn on when I put the manual gear lever into Reverse. |
As opposed to your front reverse lights? 
| Quote: |
1) Raised the rear of the Bus to allow the wheel to spin freely. This way I can put the gearbox into Reverse and allow the fluid inside to pressurize the switch. |
That's not how it works. The switch is a simple mechanical switch. You could have full gear oil or zero gear oil and it will still work (or not). A part of the shift linkage inside the transmission physically contacts the switch when you put the shifter in reverse and makes the switch close.
So you checked that you have 12v to one side of the switch with ignition on, that is correct.
Why did you not check to see if you have 12v out the other terminal of the switch when you put trans in reverse? That should tell you pretty quick whether your switch is bad.
An easier way is to take the two wires off the switch and touch them together (with ignition on). If that makes the lights turn on, then your switch is likely bad.
If that doesn't make the lights turn on, then you have a problem in the wiring between the switch and the lights somewhere.
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Tom Powell
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Joined: December 01, 2005
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Location: Kaneohe
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| Posted: Fri Feb 24, 2017 1:58 pm Post subject: Re: Rear reverse lights do not work. |
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On my '69 camper there is an inline fuse for the backup lights. The '76 wiring diagram also lists a fuse, S21 current track 65, for the backup lights. I know where the fuse is for my '69, but no idea for a '76.
I'll put $20 at 4:1 that it's the fuse. KISS
Aloha
tp |
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sjbartnik
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| Posted: Fri Feb 24, 2017 2:02 pm Post subject: Re: Rear reverse lights do not work. |
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Since he said he was getting 12v at the switch I'm gonna say it's not the fuse. But on a '76 the fuse would be inline in the wire from the coil to the switch.
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1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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DeltaBravo
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Tom Powell
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| Posted: Fri Feb 24, 2017 2:04 pm Post subject: Re: Rear reverse lights do not work. |
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I guess I'm out my $20.
Aloha
tp |
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DeltaBravo
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