This is just a write up on how I updated my 89 Comanche to have stock looking gauges with an LS Swap. I wrote this to help someone save a little money, as I did a LOT of experimentation here, and spent lot more money than I needed too. Of course your mileage may vary.
First goal was to ditch the old cluster with idiot lights for electronic gauges. So I bought a 91-96 Jeep Cherokee Factory Speedometer cluster from ebay for $60
After much research and gnashing of teeth I was able to come to the conclusion that I might be able to drive a Jeep Speedometer and Tachometer from the VSS out and Tach signals of the Chevy PCM.
So my plan was to use Jeep sensors for the Oil and Temp and tie the PCM straight to the electronic speedometer and tach. So my adventure began.
My first goal was to make ready the Cluster. I had done some various reading and found out the tach is adjustable depending of if you had a 4 or 6 cyl. Since I spent all that money on a HP Tuner, I was going to attempt to drive the tach and speedo with the chevy PCM, making whatever additional adjustments I needed in the PCM.
So I took the tach out and drilled a hole in the casing so that I could adjust it while it's plugged in. You could do this with the tach still in the casing but I wouldn’t recommend it. I also rolled the Odometer to match mine, which is NOT for the faint of heart. Also be very careful when adjusting the potentiometer it’s really not made for the abuse.
Picture of old Cluster and Connection
Picture of new Cluster and Connection
Not Used – Alt Lamp
Lamps – GND
Ign (Oil and Volt)
Not Used – Fuel
Pick a color
Note: Oil, Temp, and Tach I used the existing wires through the firewall. On my Comanche at C100 I had (Oil-C6),(Temp-D2), and (Tach-C3) you can chase further down the stream based on your application. On the PCM side of the house the Red connector holds both Speed-pin 50 DkGrn/Wht and the Tach-pin 10 Wht.
So after wiring up the cluster and accepting defeat too quickly I purchase a Digital Dakota SGI-100BT. After sticking it in line with A5 and A6, I still had no gauges - UGH!!. I later discovered that I missed a GND to B2. Suddenly the tach and speedo came to life. It’s highly possible that I didn’t need the SGI-100BT, but liked the fact that I could fine tune the tach and speedo by bluetooth, which means if I change tire sizes or gears later I have less guessing. So I left it in. If you discover that you don’t need it you can leave info in the comments.
Chevy PCM Settings:
VSS out 4000 ppm
When I went to mount the oil pressure sender, I discovered that the block had an old block heater in the way. Something I definitely don’t need here in North Carolina. I decided to take advantage of the location to place both the oil sender and temp sender closer together, which required a little more work from a mechanical point, but made wiring easier.
I bought a ICT Billet LT Gen V Engine Block M12-1.5 Coolant Crossover Feed Adapter to fill the hole in the block where the block heater stood, then drilled and tapped the hole to 3/8 NPT to hold the temp sender. (You’ll find out later that I didn’t need to do this).
After wiring and mounting the senders, I found out that the white wire in the harness I purchased for the oil pressure was not the signal. The black wire was. This pegged out my gauge, which didn’t hurt anything, so I swapped the wires and left the white wire unattached, This fixed the gauge.
So after getting all the air out of the system and finding a happy 180 degrees through the PCM. I noticed that the temp gauge was about 50 degrees off. After researching some more I found out I bought the wrong temp sensor . The 4.0L I6 has two!! One for the gauges and one for the PCM. WTF! Oh and finding a connector/pigtail for the gauge one outside a junkyard. Impossible. So I did a little temporary jeep engineering.
First I cut a screw to fit over the proper sensor. Be sure to measure your connector. My screw was too big and I had to grind it down.
Placed over the terminal.
Then filled with epoxy:
After cutting off the screw head I was left with a post.
I ended up going to the head location because I didn’t want to drain the coolant again, and was able to stop up the hole with my finger. Fortunately I had left plenty of wire to relocate.
Wrong one: https://pe-ltd.com/assets/coolant_temp.pdf
Note: I notice that with all the adaptors on the sensor that it took a little while to come up to temp, but eventually settled in. I will most likely buy another sensor and adaptor for the lower location, and swap out the next time I need to drain the coolant. I left plenty of wire just in case. May also hunt down the pigtail in the yard next time I’m there. This is what it looks like. If someone has a part number please let me know.
Gas gauge is another story. Apparently Chrysler reversed the ohm level for the float. So even though I know the fuel tank is full the gauge is pegged out at empty with the light on. I can live with that for a little while. Or at least until the tank isn't full. You can find out more info here:
Hope this helps someone.
91-96 Jeep Cherokee Factory Speedometer cluster – ebay.com
Delphi 16 Way Black Micro-Pack 100 Unsealed Female Connector - https://www.eficonnection.com/
Delphi 16 Way BLUE Micro-Pack 100 Top TPA - https://www.eficonnection.com/
Delphi 16 Way BLUE Micro-Pack 100 Bottom TPA - https://www.eficonnection.com/
Delphi Micro-Pack 100 Female Unsealed 20-22ga Terminal - https://www.eficonnection.com/
Delphi Micro-Pack 100 Female Unsealed 18-16ga Terminal - https://www.eficonnection.com/
Delphi TS10019 Engine Coolant Temperature Sensor
ACDelco PT2386 Professional Multi-Purpose Pigtail
Crown Automotive 56027012 Temperature Sensor
Standard Motor Products PS257 Oil Pressure Sender
Standard Motor Products S727 Pigtail/Socket
Digital Dakota SGI-100BT
My LS Swap Included:
ICT Billet Oil Pressure Sensor Relocation Adapter Port LS
ICT Billet LT Gen V Engine Block M12-1.5 Coolant Crossover Feed Adapter
Auto Meter 5284 LS Install Kit – Only used one fitting here. Might consider another product.
ICT Billet LS Master Adapter Set Engine Oil & Coolant Sensor
93 or 96 Cherokee ohms
89 Comanche ohms
100 Degrees – 1365 ohms
100 Degrees – 1600 ohms
220 Degrees – 93.5 ohms
180 Degrees – 309 ohms
260 Degrees – 55.1 ohms
240 Degrees – 113 ohms