What is this electrical connection for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Yukon Jack** · 03-10-2004, 01:35 PM

Here is an electrical connection that is on my 70 K5. The engine is not stock, someone put in a 400 sb.

My 69 K20 does not have this connection. Any idea what it is for?

stelth2002 · 03-10-2004, 01:36 PM

A 400 small block and a 2 barrel. OK :S

the connector actually looks like a fuse for something. Trace it

**CPNE** · 03-10-2004, 01:40 PM

It does not look stock. Where do wires lead? Is it just hanging there?

My guesses are:

Backup lights
TH400 kickdown

Neither of those makes sense with the type of connector used though.

**CPNE** · 03-10-2004, 01:41 PM

Quote:

Originally posted by stelth2002
A 400 small block and a 2 barrel. OK :S

Many of mid 70's grocery getters with a 400 had 2bbl's. Remember the oil embargo?

**Yukon Jack** · 03-10-2004, 01:45 PM

I haven't attempted to trace them yet. It has a 4 speed manual.

The 4 barrel q-jet was in the rear of the truck and this carb was swapped on at some point. I'm going to have the q-jet looked at to see if it is repairable - don't want to choke the engine with the 2 barrel, that just wouldn't be right!

I will do some tracing now that I know it doesn't appear to be a factory connection.

**CPNE** · 03-10-2004, 01:49 PM

Quote:

Originally posted by CPNE

Many of mid 70's grocery getters with a 400 had 2bbl's. Remember the oil embargo?

After looking at the pic I see it has a 4bbl intake. But I've had 2 stock 400's with a 2bbl intake, both out of mid-70's sedans so I assumed this was also a factory 2bbl.

1-PU70 · 03-10-2004, 02:25 PM

I had a 69 Impala with a 396 and a 2 barel. It was all original. I think it was the only year they put a 2 barel on a BB.

Davy · 03-10-2004, 02:29 PM

Yukon,

My 70 K5 has the exact same thing and in the same spot. My K5 is original. I think it is a resistor for the radio or something??

If I remember correctly, there is a red wire running from it to the radio. Not sure though, I currently have mine stripped down for body and paint work.

Davy

rodnok1 · 03-10-2004, 02:53 PM

If it runs to the radio hot wire it should be a RFI filter to keep your radio from buzzing. If I remember correctly GM had issues with am radios buzzing, think it is alot worse in points applications.

J.Lance · 03-10-2004, 04:38 PM

My '70 Jimmy has the exact relay in the same spot. Starting to see a pattern?? Anyway, it is identical to the 2 relays they used on '71s for the emissions stuff (cuts vacuum advance until the motor is warmed up). If you trace the wires, one should run to a temp. sending unit on the passenger side of the block, but you won't find it since the motor is not original. Two wires would run to a vacuum switch mounted inline between the vacuum advance and the carb. Another wire or two would run to a idle solenoid on the carb.

Check this post for a pic of the '71 version:

http://67-72chevytrucks.com/vboard/s...threadid=94599

Jason

SWEET7T · 03-10-2004, 04:44 PM

My '70 C10 has the relay too. I also think it has something to do with the engine temp. As my engine starts to warm up, I hear a click (just one) and it takes longer for it to do it when it is colder outside. I just never cared enough to trace the wires to see where they went, it works so I leave it alone

Alexis · 03-10-2004, 04:57 PM

my k/5 had the same thing, never had a chance to check out what it did.

**Yukon Jack** · 03-10-2004, 05:15 PM

Very interesting - thanks for all the info!

Davy · 03-10-2004, 05:23 PM

Yukon,

This was driving me crazy last night, so I looked at my harness. This "thing" has a red wire going back to the "radio" slot on the fuse panel (not straight to the radio like I originally thought). The plug-in is split, with one power leg going to the radio and one power leg going to this "thing". The blue, black and green wires coming off of this unit were dead-ended, so I can't tell what they were once hooked to.

I doubt that I will be putting this thing back on my Blazer.

Davy

03-10-2004, 01:35 PM	#1
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	What is this electrical connection for? Here is an electrical connection that is on my 70 K5. The engine is not stock, someone put in a 400 sb. My 69 K20 does not have this connection. Any idea what it is for? Attached Images __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

03-10-2004, 01:36 PM	#2
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	A 400 small block and a 2 barrel. OK :S the connector actually looks like a fuse for something. Trace it __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

03-10-2004, 01:40 PM	#3
CPNE Resident Curmudgeon Join Date: Dec 1999 Location: NH Posts: 6,664	It does not look stock. Where do wires lead? Is it just hanging there? My guesses are: Backup lights TH400 kickdown Neither of those makes sense with the type of connector used though. __________________ Currently on or near the homestead: 67 Chevy SWB 2WD stepside 350/3 on tree (Pat's) 67 GMC SWB 2WD Fleet 402/auto (Brian's under construction) 67 Chevy 3/4 ton 2WD 402/auto (Business Hauler) 67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC) 68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC) 70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC) 71 Chevy SWB stepside (Crushed by tree - parts donor) 72 Chevy 3/4 ton 4WD (Parts donor) 72 Chevy 3/4 ton 4WD Suburban (Parts Donor) 72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC) 81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler) 82 Camaro Z/28 355/Super T-10 (Pat's toy) 93 Caprice 9C1 (Brian's Cop Car) 02 Toyota Camry (Reliable but a souless steel and plastic hulk) 2011 2SS RS Camaro M6 Factory Hurst Shifter Maybe I need to sell some of this crap Yet another Bozo with a sawz-all

03-10-2004, 01:45 PM	#5
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	I haven't attempted to trace them yet. It has a 4 speed manual. The 4 barrel q-jet was in the rear of the truck and this carb was swapped on at some point. I'm going to have the q-jet looked at to see if it is repairable - don't want to choke the engine with the 2 barrel, that just wouldn't be right! I will do some tracing now that I know it doesn't appear to be a factory connection. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

03-10-2004, 02:25 PM	#7
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	I had a 69 Impala with a 396 and a 2 barel. It was all original. I think it was the only year they put a 2 barel on a BB. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

03-10-2004, 02:29 PM	#8
Davy Registered User Join Date: Apr 2003 Location: Rice, Minnesota Posts: 370	Yukon, My 70 K5 has the exact same thing and in the same spot. My K5 is original. I think it is a resistor for the radio or something?? If I remember correctly, there is a red wire running from it to the radio. Not sure though, I currently have mine stripped down for body and paint work. Davy __________________ 1970 Blazer CST Looking for NOS items for my CST restoration.

03-10-2004, 02:53 PM	#9
rodnok1 Registered User Join Date: Jun 2003 Location: Linden, North Carolina Posts: 617	If it runs to the radio hot wire it should be a RFI filter to keep your radio from buzzing. If I remember correctly GM had issues with am radios buzzing, think it is alot worse in points applications. __________________ 64 Panel Rebuild Pics Clutch Replacement and Borg Warner T10 Trans Rebuild 64 Panel 1/2 Ton 350cubes/400hp BorgWarner t-10 3:73 Auburn Posi

03-10-2004, 04:38 PM	#10
J.Lance Too many is never enough! Join Date: May 2003 Location: Idaho Falls, ID Posts: 455	relay My '70 Jimmy has the exact relay in the same spot. Starting to see a pattern?? Anyway, it is identical to the 2 relays they used on '71s for the emissions stuff (cuts vacuum advance until the motor is warmed up). If you trace the wires, one should run to a temp. sending unit on the passenger side of the block, but you won't find it since the motor is not original. Two wires would run to a vacuum switch mounted inline between the vacuum advance and the carb. Another wire or two would run to a idle solenoid on the carb. Check this post for a pic of the '71 version: http://67-72chevytrucks.com/vboard/s...threadid=94599 Jason __________________ Jason 1968 K10 SWB Fleetside 1971 K2500 GMC LWB 1968 K20 (later frame, donor body) 1972 C20 LWB parts truck 1993 K2500 Suburban, tow rig, 454, 4L80E NEW!! 18' Siem's car hauler 2004 Honda Odyssey (family man!)

03-10-2004, 04:44 PM	#11
SWEET7T Try spinnin 4 rear tars Join Date: Sep 2003 Location: Salt Lake City, Utah Posts: 757	My '70 C10 has the relay too. I also think it has something to do with the engine temp. As my engine starts to warm up, I hear a click (just one) and it takes longer for it to do it when it is colder outside. I just never cared enough to trace the wires to see where they went, it works so I leave it alone __________________ SWEET7T 1970 C10, 2wd, LB, 307/TH350/3.08. PS, PB

03-10-2004, 04:57 PM	#12
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,879	my k/5 had the same thing, never had a chance to check out what it did.

03-10-2004, 05:15 PM	#13
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,684	Very interesting - thanks for all the info! __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

03-10-2004, 05:23 PM	#14
Davy Registered User Join Date: Apr 2003 Location: Rice, Minnesota Posts: 370	Yukon, This was driving me crazy last night, so I looked at my harness. This "thing" has a red wire going back to the "radio" slot on the fuse panel (not straight to the radio like I originally thought). The plug-in is split, with one power leg going to the radio and one power leg going to this "thing". The blue, black and green wires coming off of this unit were dead-ended, so I can't tell what they were once hooked to. I doubt that I will be putting this thing back on my Blazer. Davy __________________ 1970 Blazer CST Looking for NOS items for my CST restoration. Last edited by Davy; 03-11-2004 at 12:29 PM.

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