Questions about proportioning valve and Neg battery cable - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bossrod · 11-30-2004, 08:51 PM

Can someone explain how the proportioning valve switch works? I notice that the contact pin is recessed into the switch and doesn't make contact with the connector on top. Also, can someone tell me where the Neg battery cable was originally connected on a 72' c-10. Thanks

Sweet72 · 11-30-2004, 09:13 PM

The brake warning switch located on top of the combination valve works on differential pressure. When a difference in front and rear brake pressure is detected a ground is applied to the brake warning light. The light can only be reset when equal system pressure is restored. The electrical contact should not be recessed. The battery negative lead on my '72 was bolted to the passengers cyl. head front accessory bolt hole.

bossrod · 12-01-2004, 07:22 AM

Thanks for the info.

11-30-2004, 08:51 PM	#1
bossrod Registered User Join Date: Feb 2004 Location: Groton, CT Posts: 168	Questions about proportioning valve and Neg battery cable Can someone explain how the proportioning valve switch works? I notice that the contact pin is recessed into the switch and doesn't make contact with the connector on top. Also, can someone tell me where the Neg battery cable was originally connected on a 72' c-10. Thanks

11-30-2004, 09:13 PM	#2
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	The brake warning switch located on top of the combination valve works on differential pressure. When a difference in front and rear brake pressure is detected a ground is applied to the brake warning light. The light can only be reset when equal system pressure is restored. The electrical contact should not be recessed. The battery negative lead on my '72 was bolted to the passengers cyl. head front accessory bolt hole. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction. Last edited by Sweet72; 11-30-2004 at 09:21 PM.

12-01-2004, 07:22 AM	#3
bossrod Registered User Join Date: Feb 2004 Location: Groton, CT Posts: 168	Thanks for the info.



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