Another wire I need help identifying - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Riveted1 · 10-11-2008, 02:38 PM

Replacing the beaten up engine harness in my 67. My truck has HEI now, so I ordered a M&H harness w/the HEI conversion built in. Trying to figure out what the pink/yellow and the blue wires are. I'm assuming the pink/yellow is the power for the HEI. But what is the blue? Is that a tach wire maybe? Or somewhere I saw a blue wire for an electronic oil pressure gauge? I can double check w/the meter here in a while, but thought I'd post and see if anyone knows for sure before I burn something up!

Sport/Truck · 10-11-2008, 05:17 PM

I'm guessing maybe electric choke. I ordered the same harness, but had to send it back for the electric choke wire.....
The oil pressure wire has a rubber boot on it.
s/t

ERASER5 · 10-11-2008, 09:10 PM

Why is there a yellow wire on your HEI power wire? With HEI you no longer should have a yellow wire going to the starter.

Riveted1 · 10-11-2008, 09:55 PM

Even with the old setup, I still have a yellow wire going to the starter. And I'm not sure if that even is the HEI wire, although everything else is accounted for, so it pretty much has to be..... Didn't have time to meter it tonight, will check it tomorrow and see.

S/T, I guess the blue one could be for electric choke. It can't go too far from the other wire, so that would make sense IF the other one is actually the HEI wire.

BLACK AND BLUE 67-72 · 10-11-2008, 10:06 PM

Yellow and pink are the HEI wires, and the blue is for the oil pressure sender, if you have the light only. I know this because I bought the same harness a couple of years ago, it all plugged in and has worked great!!!

BLACK AND BLUE 67-72 · 10-11-2008, 10:09 PM

ERASER5 I have the same harness and my yellow wire is hooked up to the starter, never have had any problems at all with it hooked up like this.

vectorit · 10-11-2008, 10:13 PM

Call M&H and ask for Darren, then tell him Chris with the 68 Suburban told you to call... Even thought M&H pissed me off, Darren worked with me for hours over the phone testing each circuit. He will explain what each and every wire is for you, plus he is a very patient guy that put up with me so that says a lot.

Riveted1 · 10-12-2008, 07:28 PM

Quote:

Originally Posted by BLACK AND BLUE 67-72

Yellow and pink are the HEI wires, and the blue is for the oil pressure sender, if you have the light only. I know this because I bought the same harness a couple of years ago, it all plugged in and has worked great!!!

Sweet! That's exactly what I needed!

BLACK AND BLUE 67-72 · 10-13-2008, 09:02 AM

anytime!!!

ERASER5 · 10-13-2008, 01:04 PM

Sure, you can keep the yellow wire hooked to the starter. It doesn't hurt anything. That is how the original wiring is.

However, the original coil wire-to-firewall was a resistance wire that cut the voltage to 6 volts. The yellow wire to the starter gave you a full 12 volts at start up for better spark until the starter is released.

A proper HEI power source will NOT be a resistance wire. It will be a normal wire supplying 12 volts to the coil at all times(when the key is on or starting). The yellow wire to the starter is redundant and not necessary. Check any of the FAQs on HEI conversion.

10-11-2008, 02:38 PM	#1
Riveted1 Tasty Cakes! Join Date: Apr 2003 Location: Gilbert, AZ Posts: 2,112	Another wire I need help identifying Replacing the beaten up engine harness in my 67. My truck has HEI now, so I ordered a M&H harness w/the HEI conversion built in. Trying to figure out what the pink/yellow and the blue wires are. I'm assuming the pink/yellow is the power for the HEI. But what is the blue? Is that a tach wire maybe? Or somewhere I saw a blue wire for an electronic oil pressure gauge? I can double check w/the meter here in a while, but thought I'd post and see if anyone knows for sure before I burn something up! Attached Images __________________ I'm a little and a lot Ground beef: A cow with no legs. ---------------- '66 Chevy SWB "Penny" '67 Chevy Big Window SWB- aka "Pearl" '72 Burb- "Betty" "It's not a hearse dammit" '99 Chevy Ext. cab Silverado Last edited by Riveted1; 10-11-2008 at 02:39 PM.

10-11-2008, 05:17 PM	#2
Sport/Truck Sierra Grande Club Join Date: Jan 2007 Location: New Mexico USA Posts: 2,433	Re: Another wire I need help identifying I'm guessing maybe electric choke. I ordered the same harness, but had to send it back for the electric choke wire..... The oil pressure wire has a rubber boot on it. s/t __________________ 1971 GMC Sierra Grande, 1/2 ton short wide, original 4 bolt 010 020 block & heads. (matching #'s). 383 stroker, SMI q jet 750 cfm, Lunati Voodoo 60102 cam, Scorpion roller rockers, Spin Tech pro street mufflers with X pipe.

10-11-2008, 09:10 PM	#3
ERASER5 Registered User Join Date: Jun 2006 Location: Indiana Posts: 4,859	Re: Another wire I need help identifying Why is there a yellow wire on your HEI power wire? With HEI you no longer should have a yellow wire going to the starter. __________________ '70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60

10-11-2008, 09:55 PM	#4
Riveted1 Tasty Cakes! Join Date: Apr 2003 Location: Gilbert, AZ Posts: 2,112	Re: Another wire I need help identifying Even with the old setup, I still have a yellow wire going to the starter. And I'm not sure if that even is the HEI wire, although everything else is accounted for, so it pretty much has to be..... Didn't have time to meter it tonight, will check it tomorrow and see. S/T, I guess the blue one could be for electric choke. It can't go too far from the other wire, so that would make sense IF the other one is actually the HEI wire. __________________ I'm a little and a lot Ground beef: A cow with no legs. ---------------- '66 Chevy SWB "Penny" '67 Chevy Big Window SWB- aka "Pearl" '72 Burb- "Betty" "It's not a hearse dammit" '99 Chevy Ext. cab Silverado

10-11-2008, 10:06 PM	#5
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Another wire I need help identifying Yellow and pink are the HEI wires, and the blue is for the oil pressure sender, if you have the light only. I know this because I bought the same harness a couple of years ago, it all plugged in and has worked great!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-11-2008, 10:09 PM	#6
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Another wire I need help identifying ERASER5 I have the same harness and my yellow wire is hooked up to the starter, never have had any problems at all with it hooked up like this. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-11-2008, 10:13 PM	#7
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Another wire I need help identifying Call M&H and ask for Darren, then tell him Chris with the 68 Suburban told you to call... Even thought M&H pissed me off, Darren worked with me for hours over the phone testing each circuit. He will explain what each and every wire is for you, plus he is a very patient guy that put up with me so that says a lot. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

10-13-2008, 09:02 AM	#9
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: Another wire I need help identifying anytime!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-13-2008, 01:04 PM	#10
ERASER5 Registered User Join Date: Jun 2006 Location: Indiana Posts: 4,859	Re: Another wire I need help identifying Sure, you can keep the yellow wire hooked to the starter. It doesn't hurt anything. That is how the original wiring is. However, the original coil wire-to-firewall was a resistance wire that cut the voltage to 6 volts. The yellow wire to the starter gave you a full 12 volts at start up for better spark until the starter is released. A proper HEI power source will NOT be a resistance wire. It will be a normal wire supplying 12 volts to the coil at all times(when the key is on or starting). The yellow wire to the starter is redundant and not necessary. Check any of the FAQs on HEI conversion. __________________ '70 GMC C1500 LWB Power disc brakes. WooHoo! Posi 6 Lug Dana 60 Last edited by ERASER5; 10-15-2008 at 01:25 AM. Reason: To be more correct.



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