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Old 07-07-2013, 05:33 PM   #1
k1blazer
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Reverse lamp switch

I have a 72 K5 4WD automatic (TH350). The reverse light switch is leaking when I put it into reverse. I cannot find a new switch anywhere. Any suggestions out there??
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Old 07-08-2013, 02:21 PM   #2
cleszkie
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Re: Reverse lamp switch

The reverse light switch for your Blazer is located on the steering column near the firewall. It is part of the neutral safety switch for automatic tranny equiped trucks. Only the manual tranny models have a reverse switch on the tranny itself. Not sure what you are referring to on your tranny. Post a picture of the leak, and you will certainly get an answer from someone.
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Old 07-08-2013, 02:28 PM   #3
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Re: Reverse lamp switch

Thanks cleszkie!! I'll surely get a pic as soon as I get back into town. But to explain it a little further, the switch that is leaking is just in front of the dip stick tube for the trans. Its a single wire switch. It only leaks in reverse...actually, it leaks all the time, but in reverse, the fluid sprays out.

I'll get that pic posted as soon as I can.

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Old 07-09-2013, 04:13 PM   #4
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Re: Reverse lamp switch

Not sure what that wire could be. My TH350 has no wiring. Do you have a tranny temperature gauge? Maybe it's a temp sending unit that someone installed. Pics will definitely help.
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Old 07-09-2013, 06:11 PM   #5
jaros44sr
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Re: Reverse lamp switch

Couldnt be the vacuum line off of the module, could it?
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Old 07-15-2013, 01:04 PM   #6
k1blazer
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Re: Reverse lamp switch

Definitely not the vacuum modulator or the vacuum line. Here is two pics of the switch on and off the tranny.
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Old 07-15-2013, 07:02 PM   #7
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Re: Reverse lamp switch

The switch is for the TCS system used in 1971-72. It disabled the vacuum advance in all gears except high gear. You can leave it in place unused, or remove ad plug it. That hole is the third gear pressure port.
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Old 07-15-2013, 07:05 PM   #8
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Re: Reverse lamp switch

I forgot , TCS stands for transmission controlled spark. I got this info from the Crankshaft Coalition website.
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Old 07-15-2013, 07:12 PM   #9
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Re: Reverse lamp switch

Quote:
Originally Posted by DADS1971 View Post
The switch is for the TCS system used in 1971-72. It disabled the vacuum advance in all gears except high gear. You can leave it in place unused, or remove ad plug it. That hole is the third gear pressure port.
Well that makes sense, never saw that end of the TCS system....good answer
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Old 07-15-2013, 08:50 PM   #10
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Re: Reverse lamp switch

Thank you everyone!!! It's about to get plugged!

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