I need some electrical help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70c10 · 10-11-2004, 12:11 AM

Today I was trying to get my dads heater switch working on his 70' (it has never worked on it's own). It has a toggle switch rigged up to the "ignition unfused" on the fuse panel. I tried 3 different heater controls and none work.

. When I hook up my test light, at the heater fuse it lights up, but when I test all 4 terminals on the plug it won't light up. Where should I look for the problem?. Thanks

glock35ipsc · 10-11-2004, 12:16 AM

There should be one key-on wire at the switch plug, I think it is brown in color. If you have no power at the switch plug, and the fuse is good, then there is a break in the wire between the fuseblock and the switch plug. You need to dig into the harness with a test light/DVM and test every so often until you find the break. Or, it could be right at the fuseblock connector. Gotta have power to the switch first before anything elso can be looked at.

The other three (blue, yellow, and orange) go to the resistor. Orange is "HIGH", which is basically direct to the motor. The other two are low and medium. That is, if this truck has no A/C.

hotrodtroy · 10-11-2004, 12:19 AM

Mine is rigged the same way and the blower motor seems to be bad, have you checked that yet? I have been told that they get flat spots in the brushes and may stick in that spot. GL. Let us know what you find.

70c10 · 10-11-2004, 12:32 AM

glock35ipsc, you are correct about the brown 14 gauge wire. I'm not getting juice to the end of it. The fuse is lighting up so it must have a break between the fuse and the plug. Hotrodtroy, I think the blower motor is fine because the toggle switch that is rigged up works the heater fine. Thanks guys.

10-11-2004, 12:11 AM	#1
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	I need some electrical help Today I was trying to get my dads heater switch working on his 70' (it has never worked on it's own). It has a toggle switch rigged up to the "ignition unfused" on the fuse panel. I tried 3 different heater controls and none work. . When I hook up my test light, at the heater fuse it lights up, but when I test all 4 terminals on the plug it won't light up. Where should I look for the problem?. Thanks __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

10-11-2004, 12:16 AM	#2
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	There should be one key-on wire at the switch plug, I think it is brown in color. If you have no power at the switch plug, and the fuse is good, then there is a break in the wire between the fuseblock and the switch plug. You need to dig into the harness with a test light/DVM and test every so often until you find the break. Or, it could be right at the fuseblock connector. Gotta have power to the switch first before anything elso can be looked at. The other three (blue, yellow, and orange) go to the resistor. Orange is "HIGH", which is basically direct to the motor. The other two are low and medium. That is, if this truck has no A/C. __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 10-11-2004 at 12:22 AM.

10-11-2004, 12:19 AM	#3
hotrodtroy Registered User Join Date: Feb 2004 Location: Colorado Springs, CO Posts: 138	Mine is rigged the same way and the blower motor seems to be bad, have you checked that yet? I have been told that they get flat spots in the brushes and may stick in that spot. GL. Let us know what you find. __________________ '72 C-10 w/ '68 Large Journal 327cu.in. "It's o.k. to dream about what you want to do, until you start doing what you are meant to do." Line from "The Rookie"

10-11-2004, 12:32 AM	#4
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	glock35ipsc, you are correct about the brown 14 gauge wire. I'm not getting juice to the end of it. The fuse is lighting up so it must have a break between the fuse and the plug. Hotrodtroy, I think the blower motor is fine because the toggle switch that is rigged up works the heater fine. Thanks guys. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads



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