79k20 oil pressure gauge pegs - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jpayne79k20 · 10-27-2015, 07:10 PM

I'm have alittle issues finding a form on here explaining how I need to switch the wiring pins at firewall connector. I'm pretty sure my truck came with a dummy light and someone switch it at some point. Any help would great.

Thanks, Josh

Chaplain · 10-28-2015, 10:10 AM

Start reading from here: http://67-72chevytrucks.com/vboard/s...&postcount=190

**hatzie** · 10-28-2015, 10:59 AM

Unplugged or open oil pressure sender.

0 Ω = 0 PSI
80 Ω = 60 PSI
∞ Ω = nailed gauge.

Instrument cluster plug pinouts for 73-87 trucks.
http://67-72chevytrucks.com/vboard/s...55&postcount=2

jpayne79k20 · 10-28-2015, 05:50 PM

I did replace the sending unit. I checked the ohms with not running and with running. Sending unit was in spec. So I ohm tested the single wire to firewall connector and up to dash cluster. All checked out fine. So this made me believe it was wired up wrong since it would peg with ignition on.

**hatzie** · 10-28-2015, 08:18 PM

Did you look at the pinout pages in the thread I posted? They should allow you to ID what terminals are in the wrong position if any.

Chaplain · 10-28-2015, 08:35 PM

Keep at it.

10-27-2015, 07:10 PM	#1
jpayne79k20 Registered User Join Date: Sep 2015 Location: Pottsville, Pa Posts: 18	79k20 oil pressure gauge pegs I'm have alittle issues finding a form on here explaining how I need to switch the wiring pins at firewall connector. I'm pretty sure my truck came with a dummy light and someone switch it at some point. Any help would great. Thanks, Josh

10-28-2015, 10:10 AM	#2
Chaplain Registered User Join Date: Oct 2014 Location: TN Posts: 294	Re: 79k20 oil pressure gauge pegs Start reading from here: http://67-72chevytrucks.com/vboard/s...&postcount=190

10-28-2015, 10:59 AM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: 79k20 oil pressure gauge pegs Unplugged or open oil pressure sender. 0 Ω = 0 PSI 80 Ω = 60 PSI ∞ Ω = nailed gauge. Instrument cluster plug pinouts for 73-87 trucks. http://67-72chevytrucks.com/vboard/s...55&postcount=2 __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

10-28-2015, 05:50 PM	#4
jpayne79k20 Registered User Join Date: Sep 2015 Location: Pottsville, Pa Posts: 18	Re: 79k20 oil pressure gauge pegs I did replace the sending unit. I checked the ohms with not running and with running. Sending unit was in spec. So I ohm tested the single wire to firewall connector and up to dash cluster. All checked out fine. So this made me believe it was wired up wrong since it would peg with ignition on.

10-28-2015, 08:18 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: 79k20 oil pressure gauge pegs Did you look at the pinout pages in the thread I posted? They should allow you to ID what terminals are in the wrong position if any. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

10-28-2015, 08:35 PM	#6
Chaplain Registered User Join Date: Oct 2014 Location: TN Posts: 294	Re: 79k20 oil pressure gauge pegs Keep at it.

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