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Old 06-12-2021, 12:31 AM   #1
71CHEVYSHORTBED402
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Ha - Is this the electrical I have to look forward to?

Alright man, what's going on here anyway? Bad enough I'm colored blind, though I trained my eyes to adjust for wires if I apply some effort. Yeah tans, orange, green and BS, half the time black looks brown

Anyway, so I got some elect harnesses, which is good news, pulled the easy one and compared it to the old. Now I could probably guess but that gets me into trouble, but my original harness wasn't anything like this. For what it's worth, that green wire nearest the plug is probably for my temp. sender, pretty sure the one is for HEI. If that's the sender wire it's due I'm stuck with a temp. sender on the RH head Nice adapter if that's it.

I sent this picture to the distributor, they're one of the two players. I asked for a source for common harnesses connectors and that, see what happens. Looked up the part #, came up empty.

I'm green, but I did tag all the original wiring, so okay on that end. Picked up a multimeter I don't know how to use yet, but I know a test light at least Any suggestions how to proceed testing circuits, such as perhaps an adequate battery for the task or?

If I were to assume this harness included the A/C compressor (COUGH!) any recommendations for a kit with proper connectors?

Other than that, seems to me the new harnesses aren't like the old really, perhaps an improvement. This is their "HEI Harness", passes through the firewall gutter. If that's their blower motor connect (COUGH!) for instance, the old one came through the firewall, not through the firewall gutter, same for the A/C compressor.

Suggestions always appreciated.
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony
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Old 06-12-2021, 03:40 AM   #2
87Skier
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Re: Ha - Is this the electrical I have to look forward to?

1 & 2 - look like starter. Some starters will have two wires. Tape up the one you don't use.

3 - Looks like HEI distributor connector

4 - I would guess A/C but I've never looked at A/C truck wiring

5 - Could be for electric choke. Looks similar to my 80's choke setup

6 - Temp gauge

7 - Fuel gauge?

8 - Brake valve

9 - unsure what the connector is for

----------------------------

If you have a multimeter then set it to ohms on each auto or the lowest setting. You need to probe each end of the wire. Put one probe in at the main connector and the other at the other end of the wire.

It should read as less than 5 ohms, anything more indicates an issue.

You can do something similar with a test light by hooking up one end of the wire to the positive battery terminal, connecting the negative clip of the test light to the negative battery then probing the wire.

The downside is that test lights don't draw enough power to tell you if the wire will hold up to the rated current. A multimeter gives you a better indicator by telling you how much resistance is on the wire. More resistance means more your distributor, starter and AC compressor are getting less power than they should.

Besides doing a test fit there isn't anything more you need to test.
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Old 06-12-2021, 12:17 PM   #3
71CHEVYSHORTBED402
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Re: Ha - Is this the electrical I have to look forward to?

Quote:
Originally Posted by 87Skier View Post
1 & 2 - look like starter. Some starters will have two wires. Tape up the one you don't use.

3 - Looks like HEI distributor connector

4 - I would guess A/C but I've never looked at A/C truck wiring

5 - Could be for electric choke. Looks similar to my 80's choke setup

6 - Temp gauge

7 - Fuel gauge?

8 - Brake valve

9 - unsure what the connector is for

----------------------------

If you have a multimeter then set it to ohms on each auto or the lowest setting. You need to probe each end of the wire. Put one probe in at the main connector and the other at the other end of the wire.

It should read as less than 5 ohms, anything more indicates an issue.

You can do something similar with a test light by hooking up one end of the wire to the positive battery terminal, connecting the negative clip of the test light to the negative battery then probing the wire.

The downside is that test lights don't draw enough power to tell you if the wire will hold up to the rated current. A multimeter gives you a better indicator by telling you how much resistance is on the wire. More resistance means more your distributor, starter and AC compressor are getting less power than they should.

Besides doing a test fit there isn't anything more you need to test.
Thanks a bunch for all that & clear tips too. Some guy was telling me you can test with a 9 volt, I suppose you could but the multimeter will be great, thank you.

1 & 2 - Yep, starter,. I have the impression starters for HEI are one wire. So much for "custom" made

3 - Looks like HEI distributor connector I think so too and it would fit.

4 - I would guess A/C but I've never looked at A/C truck wiring. It probably is A/C. However the compressor takes a black flat plug for two prong with a ground terminal & dark greenish wire. Theirs is a single prong in pink or some BS Beyond that what's throwing me is the original A/C harness came through the firewall. My guess is they simplified the wiring and might be easier.

5 - Could be for electric choke. Looks similar to my 80's choke setup. I have the original mechanical choke.

6 - Temp gauge Interesting. If so that was their provision for the sender on the wrong head. Two wires on that connector, perhaps the single wire plugs into #9. If so that should work well. What are the odds their clips such as for valve cover are in the right place I'll probably pull them anyway, prefer black, the Caldwell blackening & sealant is nice for what worth.

7 - Fuel gauge? Heck I don't know. I had the same wire on the old harness that was plugged into the TCS configuration. Fuel gauge runs to the sender.

8 - Brake valve Yep

9 - unsure what the connector is for See 6
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony
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Old 06-12-2021, 07:00 PM   #4
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Re: Ha - Is this the electrical I have to look forward to?

5 might be the TH400 kickdown wire. My 68 Impala had that as part of the on engine linkage. At some point, that moved to the cab as part of the in cab gas pedal setup.

9 Many vehicles from that era had an AC fuse as part of the AC wiring harness. If that is a 2 slot connector, might be for the AC fuse.

7 would be about right for an electric oil sender wire but I thought most 71s had a mechanical sender.

Where is(are) the wire(s) for the Alternator?

A lot of AC equipped vehicles had an idle solenoid that sat on the driver's side of the carb. It would be a single wire that would also tie to the AC compressor wire. When the compressor switched on, the solenoid would advance the idle speed a bit to prevent stalling.
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Old 06-15-2021, 11:56 AM   #5
71CHEVYSHORTBED402
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Re: Ha - Is this the electrical I have to look forward to?

Just got off the phone with the rep, real nice guy. Turns out these aren't custom at all, this harness serves various purposes, and they have connectors if a guy wants to install all the old stuff like TCS & idle stop.

Note: He suggests attaching #1 to the starter HEI or not. Wasn't clear to me why but what the heck, I'll attach it to the starter.

Had to edit the former image, #6 # 9 was jacked up badly YIKES! Per vendor these are......
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony

Last edited by 71CHEVYSHORTBED402; 06-15-2021 at 10:34 PM.
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Old 06-15-2021, 06:23 PM   #6
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Re: Ha - Is this the electrical I have to look forward to?

I had to revise the image post above, what a disaster

Sure little information on TCS and that. Some information, seems to be a mix but two senders on some trucks. http://67-72chevytrucks.com/vboard/s...d.php?t=577620

Edit: From what the distributor told me #6 & #9 is for engine temperature sender, and they didn't alter the harness at all. Many opinions are the temp. gauge sender is supposed to be on the LH head. Seems to fit better with the sender on the RH head, though the wire jumps back over to the LH side on my other 402. I can't speak for correct on either truck.
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony

Last edited by 71CHEVYSHORTBED402; 06-15-2021 at 10:31 PM.
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Old 06-16-2021, 03:47 PM   #7
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Re: Ha - Is this the electrical I have to look forward to?

The #5 connector looks like one used on an oil pressure switch
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Old 06-27-2021, 03:42 PM   #8
71CHEVYSHORTBED402
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Re: Ha - Is this the electrical I have to look forward to?

I'm cutting the yellow wire to the starter unless someone talks me out of it, soon Thing is the harness distributor says connect to "R" regardless due something or another voltage. Pretty sure I mentioned this install had a mini starter, and their harness is for both HEI or points. Not sure why he'd say that, maybe he figured I was using an original starter. Seems to be the circuit is dead anyway without a starter coil, though I'm pretty green to it.

Far as I know there's no such thing as a GM mini starter with an "R" terminal, I think those came with HEI or soon after? "Points are pointless" same with a B/A starter in some opinions.

Poll, I only need one

A. Cut it & provisions
B. Put it somewhere?
C. A
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony
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Old 06-27-2021, 03:48 PM   #9
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Re: Ha - Is this the electrical I have to look forward to?

B. bend it back , and tape it to the existing black tape.









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Old 06-27-2021, 04:09 PM   #10
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Re: Ha - Is this the electrical I have to look forward to?

Quote:
Originally Posted by Getter-Done View Post
B. bend it back , and tape it to the existing black tape.









.
ThanksI'll cut the connector off, do that and call it a day. Wish I knew what kind of braided loom and high temp. tape they use on these new harnesses. The tape @ Inline Tube & loom at Summit leaves something to be desired. Oh well, I'm using it.
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony
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Old 06-27-2021, 04:19 PM   #11
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Re: Ha - Is this the electrical I have to look forward to?

I have used something like this in the past.
It worked great.

Link: https://www.jegs.com/i/Thermo-Tec/893/18051/10002/-1









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Old 06-28-2021, 02:16 AM   #12
71CHEVYSHORTBED402
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Re: Ha - Is this the electrical I have to look forward to?

Quote:
Originally Posted by Getter-Done View Post
I have used something like this in the past.
It worked great.

Link: https://www.jegs.com/i/Thermo-Tec/893/18051/10002/-1


.
I believe this is what's on the M&H harness, though it looks brown to me in this picture, those on the harness are black. If it's the same it's real nice loom and doesn't come apart like what most of the outlets are selling. https://www.amazon.com/Pico-8213PT-F...ustomerReviews

I want to say this is like the tape on the harness, again better than common. If it's worth doing once it's worth doing twice I figure Hopefully it's what I'm looking for. The common tape is almost identical the common braided loom if a person is looking to match though. Personally I prefer the materials used on the new harness, it's nice quality. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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71 Custom Deluxe, SWB, 2WD, 402/400TH. Oh sure, I should be able to rebuild this truck for 18K. How is it a frame-off when the frame is the last thing left☺

72 Cheyenne Super, C20, 402/400TH, A/C. Very much a giving donor, beat-up hauler & naturally vented. Does what I need it to and that's it, meaning most of the cab components don't work.

Tony
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