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Old 01-09-2019, 05:42 AM   #1
broberson
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Which wires for reverse? Brake warning light?

I bought a wiring harness from Brothers Trucks, and its from american autowire. My problem is this. I知 trying to wire the reverse lights, but I dont have any loose wires to make a connection under the steering column. The instructions that came with the kit dont even list the wiring for the reverse lights. I have the original harness and I have used a few of the connections to attach wires as I致e needed. I have the plug for the reverse lights, but I dont know where or which wires to cut and attach the plug to in order to connect it to the steering column.

My next question concerns the brake warning? light. This wire comes out of the bottom of the brake fluid resevoir. Do I need to utilize this plug/wire in order for the brake lights to work, or is this simply the brake warning wire that tells you when there is an isssue witht the brake system? I have the two tan wires on the instrument cluster #2 pin that arent connected to anything.

Thanks for any help, guys.
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Old 01-09-2019, 10:06 AM   #2
TruDom
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Re: Which wires for reverse? Brake warning light?

if you have an automatic the switch is on the bottom of the steering column.
https://www.americanautowire.com/wp-...3.34.26-PM.png
2 connectors on left are reverse and the 2 on the right are for the neutral safety.

yes that is the brake warning wire.


Where are you in austin? im just finishing the install on my AAW kit on my truck. could give you a hand.
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Old 01-09-2019, 11:00 AM   #3
broberson
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Quote:
Originally Posted by TruDom View Post
if you have an automatic the switch is on the bottom of the steering column.
https://www.americanautowire.com/wp-...3.34.26-PM.png
2 connectors on left are reverse and the 2 on the right are for the neutral safety.

yes that is the brake warning wire.


Where are you in austin? im just finishing the install on my AAW kit on my truck. could give you a hand.

Ok, awesome. I thought I had those right. Where then do i go now? Where do I splice the brake wire and which wires do I splice to plug into the reverse plug?

I知 in Buda, right behind cabelas! That壇 be great to have a hand, I壇 really appreciate it!
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Old 01-09-2019, 03:38 PM   #4
TruDom
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Re: Which wires for reverse? Brake warning light?

if you bought the harness for this truck
https://www.americanautowire.com/PDF...20IN%203.1.pdf

on sheet 2 the top right shows a pic of a purple split wire with connectors. that plugs into the neutral safety switch and connects to the 2 purple wires coming out of the main harness. (no splicing and no terminals to solder on)

the backup switch is #7 on that sheet and looks like you solder on connectors and an 'L' plastic piece. plug right into backup switch.

the brake switch #5 (is above the middle of the steering column. Way up there)
looks like this https://www.partsgeek.com/assets/pro...0-MKMQXTM3.jpg
should not have to solder or splice anything. it should just clip on.


i could probably come by this weekend if you are still having trouble.
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Old 01-09-2019, 06:36 PM   #5
broberson
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Quote:
Originally Posted by TruDom View Post
if you bought the harness for this truck
https://www.americanautowire.com/PDF...20IN%203.1.pdf

on sheet 2 the top right shows a pic of a purple split wire with connectors. that plugs into the neutral safety switch and connects to the 2 purple wires coming out of the main harness. (no splicing and no terminals to solder on)

the backup switch is #7 on that sheet and looks like you solder on connectors and an 'L' plastic piece. plug right into backup switch.

the brake switch #5 (is above the middle of the steering column. Way up there)
looks like this https://www.partsgeek.com/assets/pro...0-MKMQXTM3.jpg
should not have to solder or splice anything. it should just clip on.


i could probably come by this weekend if you are still having trouble.
The pic of the harness you have isnt the same one I got. Mine was the 20 circuit from brothers here: https://www.brotherstrucks.com/DELUXE-20-CIRCUIT-WIRING-HARNESS/productinfo/UWH0018/

I致e wired up the neutral safety switch w the purple wires, the brake light with the orange and white, but I知 having trouble finding where to splice into in order to plug in the reverse lights, and where to put the brake warning light. The instrument cluster plug I have is attached below. The two wires I have left are the two tan wires on pin #2. I知 not sure if I connect the brake warning lamp to one wire, and take the other one to the ignition, or what. I知 making good progress, I知 just at a spot where I知 handcuffed because all the stuff I have left is dependant on specific wiring.
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Old 01-11-2019, 10:05 AM   #6
TruDom
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Re: Which wires for reverse? Brake warning light?

im not following what you are trying to do with the reverse lights. the reverse lights just go from fused circuit coming from fuse block through the reverse switch and then out to rear harness. (its essentially one wire from fuse block to reverse light bulb socket with a switch in the middle)

is that the old pic of the gauge connector?
im not an expert but i have no idea why you have 2 wires there.
the brake warning light circuit: power starts from instrument panel light circuit through brake warning light bulb then tan wire to gauge connector then tan wire through firewall panel to the brake warning switch on the brake combination valve. if that switch moves it closes the circuit to ground; causing the light bulb in your instrument panel to light up.

cant help you beyond that.
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Old 01-11-2019, 02:55 PM   #7
VetteVet
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Re: Which wires for reverse? Brake warning light?

Quote:
Originally Posted by TruDom View Post
im not following what you are trying to do with the reverse lights. the reverse lights just go from fused circuit coming from fuse block through the reverse switch and then out to rear harness. (its essentially one wire from fuse block to reverse light bulb socket with a switch in the middle)

is that the old pic of the gauge connector?
im not an expert but i have no idea why you have 2 wires there.
the brake warning light circuit: power starts from instrument panel light circuit through brake warning light bulb then tan wire to gauge connector then tan wire through firewall panel to the brake warning switch on the brake combination valve. if that switch moves it closes the circuit to ground; causing the light bulb in your instrument panel to light up.

cant help you beyond that.
The brake warning light gets it's power from the fuel gauge terminal. The tan wire is a grounding wire to the switch in the proportioning valve by the master cylinder, BUT there is also a wire from the switch in the prop valve to the ignition switch which grounds the prop valve switch when the engine is cranking to check the light bulb. The wires to ground the light during cranking vary with years, some are run from the prop valve switch to the ignition switch and then to the cluster plug, and some are run from the ( two wires on the ignition switch) cluster plug to the prop valve switch and from the cluster plug to the ignition switch. ( two wires on the cluster plug.)

Power for the brake warning light on the gauge cluster Off terminal 3 to the fuel gauge. Purple line.

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Light cluster wiring shows two wires off cluster plug terminal 2, one to key switch and one to the Prop valve switch. Ignore the black arrows on the key switch wire 12 gauge brown. It is the power feed wire to the fuse panel for the wipers heater and turn signal switch.

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Key switch for 1968 and later with two tan (brown), wires for BW light and two green wires for temperature warning light.

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Old 01-11-2019, 03:06 PM   #8
broberson
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Re: Which wires for reverse? Brake warning light?

To answer a question, I am attempting to determine which wire is used to power the reverse switch and which wire is used as the backup lights on the other side of the reverse switch. I talked to a guy from american autowire and he was saying to piwer the switch with an accessory wire that is fused and run with the key on and in run position.

I hopefully have wired everything correctly, but I havent installed the gauge cluster just yet, but the truck starts, runs, idles, and turns off, so I知 hoping I did everything correctly.

The brake warning light was routed to the ignition switch on the tan wire, and then routed to the instrument cluster plug. As soon as I get everything done tonight, I値l update with the results. Thanks to everyone for your input and help!
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Old 01-12-2019, 12:10 AM   #9
zicc1835
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Re: Which wires for reverse? Brake warning light?

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Old 01-12-2019, 12:49 AM   #10
VetteVet
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Re: Which wires for reverse? Brake warning light?

Look for a fuse in the fuse panel that is labeled " B/U LPS ". It is the backup lights fuse. There should be a light green wire coming off the back side of the
fuse panel that will run to the backup light switch/ (neutral safety switch), on the steering column. Then a darker green wire will run from there through the firewall in the harness to the rear backup lights. these wires are powered by the key on powered fuse in the fuse panel and the backup portion of the NSS will close when the shifter is placed in reverse.

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The fuse is in the bottom vertical row on the right.


Here is another view.



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The light green wire runs to the NSS. shown here on top of the column. The green wires and the purple wires go to this switch. As been said in previous posts.




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From there they run out to the rear in the tail/brake/signal light harness.

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