1979 K10
Full Access Member
- Joined
- Jun 8, 2021
- Posts
- 61
- Reaction score
- 88
- Location
- Flagstaff, Arizona
- First Name
- Terrell
- Truck Year
- 1979
- Truck Model
- K10
- Engine Size
- 400
Here's a quick write up while this is still fresh in my mind. I picked up a 1986 K5 Blazer Custom Deluxe that had the basic cluster with only Speedometer, Large Fuel Gauge and 4 idiot lights for Battery, Oil, Temperature, Brake. I picked up another cluster at the junkyard. It was a 80s gauge cluster with 85mph speedo, and gauges for Battery Voltage, Oil Pressure, Engine Temperature.
Replace coolant and oil pressure switches with sensors.
If your truck orignally came with Idiot lights, you need to replace the coolant temp sensor on the side of the block with whatever rockauto or your favorite parts source says is needed for Gauge. I used SMP TS76. Connect your original temp wire to the new temp sensor.
You also need to replace the oil pressure switch on the back of the intake by the distibutor with an oil pressure sensor for gauge. I used SMP PS154. I had to use a 1" 1/16 shallow socket to get the old oil pressure switch out of the back of the engine block. Unfortunately the new oil pressure sensor won't just thread in because it is too large and hits the back of the intake. I'll have to go to the local hardware store and look for a 1/8" NPT male to 1/8" NPT female 45 degree fitting so I can angle the Oil pressure sensor away from the intake and distributor. If anyone knows the part number for this fitting let me know.
Something like this should work
After disconnecting the oil pressure switch, I noticed my choke no longer opened when key was on, checked voltage at electric choke and nothing. Turns out the oil pressure switch is needed to provide power to the choke. I just made a jumper wire and connected the 2 pins of the oil pressure switch plug togeather and now my carb choke gets 12v with key on. I then ran a single terminal wire from the oil pressure sensor into the cab to the back of the cluster PIN 5 on the 18 PIN instrument cluster. Oil pressure gauge will peg past 60 aka 3 o clock position when not hooked to sensor. Will show 0 when grounded or hooked to oil pressure sensor and engine off.
The below pic is what finally helped me to get all the gauges functional. FYI the wire colors sometimes vary between years but most of mine matched up. I followed the 1978-87 Factory Gauges column
A pick, tiny flat tip or large paper clip works great to unpin the metal pins from the connector, then bend the locking tab back up on each pin before re-inserting so it will lock into it's new positoin.
I'll have to take a pic of the finished plug but I ended up abandoning some PINS that were originally in my instrument cluster plug.
You MUST have grounds at PIN 3,8,10. If you don't have all 3 grounds then add them or else your gauges will be wonky and wierd things happen when dash lights on or turn signals.
You MUST have 12V switched power at PIN 4,6,16
My fuel gauge was pegged past Full at the 3 oclock position, I finally fixed the gauge by trying different color wires and switching between PINs 7,18. Fuel gauge needs both PINS occupied to read fuel level and display correctly on gauge.
I am also adding the large factory tach to replace the fuel gauge in the near future and adding the small fuel gauge in the lower left corner of gauge cluster. I am doing this on the cheap-ish by re-using the standard gauge cluster circuit board and housing. More to come...
Replace coolant and oil pressure switches with sensors.
If your truck orignally came with Idiot lights, you need to replace the coolant temp sensor on the side of the block with whatever rockauto or your favorite parts source says is needed for Gauge. I used SMP TS76. Connect your original temp wire to the new temp sensor.
You also need to replace the oil pressure switch on the back of the intake by the distibutor with an oil pressure sensor for gauge. I used SMP PS154. I had to use a 1" 1/16 shallow socket to get the old oil pressure switch out of the back of the engine block. Unfortunately the new oil pressure sensor won't just thread in because it is too large and hits the back of the intake. I'll have to go to the local hardware store and look for a 1/8" NPT male to 1/8" NPT female 45 degree fitting so I can angle the Oil pressure sensor away from the intake and distributor. If anyone knows the part number for this fitting let me know.
Something like this should work
After disconnecting the oil pressure switch, I noticed my choke no longer opened when key was on, checked voltage at electric choke and nothing. Turns out the oil pressure switch is needed to provide power to the choke. I just made a jumper wire and connected the 2 pins of the oil pressure switch plug togeather and now my carb choke gets 12v with key on. I then ran a single terminal wire from the oil pressure sensor into the cab to the back of the cluster PIN 5 on the 18 PIN instrument cluster. Oil pressure gauge will peg past 60 aka 3 o clock position when not hooked to sensor. Will show 0 when grounded or hooked to oil pressure sensor and engine off.
The below pic is what finally helped me to get all the gauges functional. FYI the wire colors sometimes vary between years but most of mine matched up. I followed the 1978-87 Factory Gauges column
A pick, tiny flat tip or large paper clip works great to unpin the metal pins from the connector, then bend the locking tab back up on each pin before re-inserting so it will lock into it's new positoin.
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I'll have to take a pic of the finished plug but I ended up abandoning some PINS that were originally in my instrument cluster plug.
You MUST have grounds at PIN 3,8,10. If you don't have all 3 grounds then add them or else your gauges will be wonky and wierd things happen when dash lights on or turn signals.
You MUST have 12V switched power at PIN 4,6,16
My fuel gauge was pegged past Full at the 3 oclock position, I finally fixed the gauge by trying different color wires and switching between PINs 7,18. Fuel gauge needs both PINS occupied to read fuel level and display correctly on gauge.
I am also adding the large factory tach to replace the fuel gauge in the near future and adding the small fuel gauge in the lower left corner of gauge cluster. I am doing this on the cheap-ish by re-using the standard gauge cluster circuit board and housing. More to come...
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