Gauge questions

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

CRM

Full Access Member
Joined
Jun 6, 2016
Posts
1,188
Reaction score
2,775
Location
Pasco, Washington
First Name
Casey
Truck Year
1985
Truck Model
K2500
Engine Size
350 CI
I've read a lot of threads on gauges and I am trying to narrow down a way to go about troubleshooting. My oil pressure gauge reads 45 psi. My voltage gauge (engine running) is 17v. My temp gauge (engine warmed up) reads 145*. My gas tank gauge reads at about 2 o'clock. I know that there are no resistors on the back of the gauges. Should all the gauges have resistors installed behind them?
 

CRM

Full Access Member
Joined
Jun 6, 2016
Posts
1,188
Reaction score
2,775
Location
Pasco, Washington
First Name
Casey
Truck Year
1985
Truck Model
K2500
Engine Size
350 CI
I received 2-5w 90 ohm resistors today. Should I install them on the fuel and voltage gauges?
 

75gmck25

Full Access Member
Joined
Oct 13, 2016
Posts
2,305
Reaction score
2,281
Location
Northern Virginia
First Name
Bruce
Truck Year
1975
Truck Model
K25 Camper Special TH350 NP203
Engine Size
5.7
I would start out by ensuring the gauge cluster is properly grounded. On older trucks it’s a black wire grounded to a post on the emergency brake mechanism, and on newer trucks there is a ground bar/ ground point mounted up under the dash above the pedals.

Then start checking the wires to each sending unit. For example, ground the wire for the temp sensor and the gauge should read full hot. With high resistance (3k ohm?) it will read low and with your 90 ohm resistors it should be about 240-250 degrees. However, GM changed the gauges and senders over the years, so yours may need a different sending unit to read correctly.
 

Forum statistics

Threads
44,422
Posts
957,411
Members
36,769
Latest member
Bowtie72
Top