source to tap into interior dash lights - aux switches - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Lucasd2002 · 07-14-2023, 05:36 PM

I'm adding some auxiliary switches to my truck and the new switches have connections for the dash light circuit so they can illuminate at night or whenever the headlights are on.

I was planning to add a posi-tap onto a source wire behind the dash.

Is there a typical source that people use for this? Instruments? My vintage air HVAC? Does it matter where I tap in?

Thanks in advance

truck is a 1988 GMC crew cab v3500.

**HOTFUN** · 07-14-2023, 10:13 PM

Most of the GM trucks it is a solid gray wire for the dimmable dash lighting cluster circuit under dash. T tap that gray wire for the power to your lamp.

Lucasd2002 · 07-15-2023, 03:20 PM

Quote:

Originally Posted by HOTFUN

Most of the GM trucks it is a solid gray wire for the dimmable dash lighting cluster circuit under dash. T tap that gray wire for the power to your lamp.

Thanks man!

MalibuSSwagon · 07-19-2023, 09:38 AM

There is actually a tap on the fuseblock, for 81+ anyways, for the interior dash lamps. It's the slot labeled D "LPS" on the diagram. Diagrams from my 86 factory manual

406 Q-ship · 07-19-2023, 12:53 PM

Look at the fuse block for a blade connector right next to the instrument lamp fuse (usually the short fuse on glass fuses). That tap will be marked for instrument lamps, use that for you add on gauges.

Lucasd2002 · 07-20-2023, 05:04 PM

Thanks for all the responses guys!

Running a line from the fuse box would be ideal and simplify everything.

After looking for the correct connector to tap into the "LPS" port of the fuse box... I'm a little confused.

I found the following info here on this site.

NW-784800 for the non-piggyback "BAT" connector.
NW-784801 for the piggyback "BAT" connector.
NW-784802 for the non-piggyback "IGN" connector.
NW-784803 for the piggyback "IGN" connector.

Is there one for the "LPS" port? Will this one work?

Should I just use a standard spade connector?

edit: this kit looks like it might be relevant

MalibuSSwagon · 07-21-2023, 08:04 AM

I've always used spade connectors or pigtails I clipped out of junkyard trucks. But that Summit link looks legit, think I'm going to have to order it and see if that works! Trying to make everything legit now and I always knock out the spade connector for my OBD2/Check Engine light when I'm under the dash.

07-14-2023, 05:36 PM	#1
Lucasd2002 Registered User Join Date: Nov 2016 Location: GA Posts: 8	source to tap into interior dash lights - aux switches I'm adding some auxiliary switches to my truck and the new switches have connections for the dash light circuit so they can illuminate at night or whenever the headlights are on. I was planning to add a posi-tap onto a source wire behind the dash. Is there a typical source that people use for this? Instruments? My vintage air HVAC? Does it matter where I tap in? Thanks in advance truck is a 1988 GMC crew cab v3500.

07-14-2023, 10:13 PM	#2
HOTFUN Senior Member Join Date: Jan 2001 Location: Lincoln, Nebraska Posts: 2,149	Re: source to tap into interior dash lights - aux switches Most of the GM trucks it is a solid gray wire for the dimmable dash lighting cluster circuit under dash. T tap that gray wire for the power to your lamp. __________________ '66 CST BBW swb fleet 327 fac ac '67 CST 4x4 swb 327 factory #'s V8 stepside project '72 Cheyenne K20 50k original '72 CST Blazer K5 owned 30+yrs '73 Sierra swb 4x4 '74 Cheyenne Super swb w/16k actual '71 & 72 Cheyenne K10 4x4 swb's '70 426 HEMICUDA conv SHAKER 4 sp Dana 60 '60 Impala conv 3rd owner '72 GMC K2500 4x4 '59 Apache CST BBW fleetside swb 283 '73 ElCamino SS LS1 T56 true SS bucket tach '76 ElCamino SS 52k survivor '87 Grand National 41k True 2nd to last built in 1987. '86 K30 454 SRW fleetside CA since new '88 Trans Am GTA 39k bought new 2018 DEMON plum crazy @ 840HP! "Need for speed"

07-19-2023, 09:38 AM	#4
MalibuSSwagon Registered User Join Date: Sep 2009 Location: Weare,NH Posts: 1,592	Re: source to tap into interior dash lights - aux switches There is actually a tap on the fuseblock, for 81+ anyways, for the interior dash lamps. It's the slot labeled D "LPS" on the diagram. Diagrams from my 86 factory manual Attached Images __________________ Eric 1992 Oldsmobile Custom Cruiser 1986 Chevrolet C10\|5.3L\|TKO600\|Shortbed\|Custom Deluxe 1983 Malibu Wagon\|TPI 305\|T5 5 speed\|3.73 non-posi

07-19-2023, 12:53 PM	#5
406 Q-ship Registered User Join Date: Oct 2010 Location: Largo Florida Posts: 632	Re: source to tap into interior dash lights - aux switches Look at the fuse block for a blade connector right next to the instrument lamp fuse (usually the short fuse on glass fuses). That tap will be marked for instrument lamps, use that for you add on gauges. __________________ Lifes journey is not to arrive at the gate well preserved, it is to slide in sideways all used up and wore out yelling.....God what'a ride! Where patience fails, force prevails Stapp's Ironical Paradox "The universal aptitude for ineptitude makes any human accomplishment an incredible miracle."

07-20-2023, 05:04 PM	#6
Lucasd2002 Registered User Join Date: Nov 2016 Location: GA Posts: 8	Re: source to tap into interior dash lights - aux switches Thanks for all the responses guys! Running a line from the fuse box would be ideal and simplify everything. After looking for the correct connector to tap into the "LPS" port of the fuse box... I'm a little confused. I found the following info here on this site. NW-784800 for the non-piggyback "BAT" connector. NW-784801 for the piggyback "BAT" connector. NW-784802 for the non-piggyback "IGN" connector. NW-784803 for the piggyback "IGN" connector. Is there one for the "LPS" port? Will this one work? Should I just use a standard spade connector? edit: this kit looks like it might be relevant Last edited by Lucasd2002; 07-20-2023 at 06:48 PM. Reason: added link

07-21-2023, 08:04 AM	#7
MalibuSSwagon Registered User Join Date: Sep 2009 Location: Weare,NH Posts: 1,592	Re: source to tap into interior dash lights - aux switches I've always used spade connectors or pigtails I clipped out of junkyard trucks. But that Summit link looks legit, think I'm going to have to order it and see if that works! Trying to make everything legit now and I always knock out the spade connector for my OBD2/Check Engine light when I'm under the dash. __________________ Eric 1992 Oldsmobile Custom Cruiser 1986 Chevrolet C10\|5.3L\|TKO600\|Shortbed\|Custom Deluxe 1983 Malibu Wagon\|TPI 305\|T5 5 speed\|3.73 non-posi



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