Converting your Orange face to White face gauges, NA models

Converting your Orange Gauges (84-86) to White Gauges (87-89), NA models:

Ok guys (and gals), this is my first write-up so please excuse any mistakes or wrong information, as I have tried to make sure that there are none.
This write-up consists of how I swapped my 86 NA orange face gauges with 87 NA white face gauges. There is a difference between 86 and 84-85, as I think those two years are similar, mostly just wire colors and some pin locations. I can only outline the differences and the complications associated between 86 and 87, because that was the harness I got and I assume all 87-89 are the same.
On a scale from one to ten, I’ll give this a swap/mod a three and a half. Mostly because all your going to be doing is matching wire colors. Feel free to pm me with corrections, suggestions, or questions.

First off a disclaimer: if anything happens to you or your car because you don’t know what you are doing or you don’t take caution, I AM NOT RESPONSIBLE! By reading, looking at, or following this guide you assume all risks and liabilities associated with this swap. PLEASE take the proper steps to insure your safety as well as that of your vehicle. I don’t want pm’s or posts stating that you burned your car to the ground or that you died, because you didn’t have a clue as to what you’re doing. If you can’t read a wiring diagram, you probably should not attempt this.

A few questions come up when attempting this swap:
-Why do it? Well I did it because I blew my tranny, and swapped in a 71C from an 88. 87-89 have speed sensor type transmissions, as opposed to the 84-86 which are speed cable.
-What are the benefits/drawbacks? Benefits: IMO a more accurate speedometer reading. Drawbacks: It still lights up orange.
-What other complications or issues will arise from doing this swap? Only one I can think of is the engine temp gauge taking a bit longer to get the right reading. I would suggest you buy an aftermarket gauge anyways, especially if you live in a hot state (like me in AZ).

With all that said, onto the swap.
First off, my car does not have the following:
-A/C or heater
-Cruise control
-Factory alarm system.

The good thing is that these accessories are part of the body harness, and they should not be affected as you are only changing out the clusters. They may travel through the dash harness, but double check with the FSM to be sure.

Tools needed:
-Metric sockets and wrenches
-Phillips and flat head screw drivers
-Rachet and extension
-Wire stripper/crimper
-Soldering gun and solder (or you could cheap out and use butt connectors and tape, although not recommended)
-Heat shrink tubing
-Knowledge of electrical diagrams
-A couple of hours and a friend to keep you company.

Parts/items needed for this swap to work:
-Fsm from the year the gauges are from, as you will need the wiring diagrams for the main gauges and the volt/oil pressure gauges.
-87-89 gauge cluster(s) (speedo/tach cluster and volt/oil pressure combo)
-87-89 dash harness, (just need it for the pigtails and/or spare wiring)
-Your 84-86 gauges and harness. The harness you will use/solder in with the new pigtails. You will need the gauges to know where to wire everything to or so you know what you’re looking for.
-Speed sensor from 87-89, with enough wiring attached to it. If you can get the pigtail with it, that’s great, not necessary though. I read somewhere that each rear end (i.e. 3.70, 3.54, and 3.90) has a different number of teeth on the speed sensor drive. I had no choice so I made do with the 88 sensor, but you could very well use the sensor from a car with the same rear end as yours.

Step #1
Start by disconnecting your battery, removing your steering wheel and switches on the steering shaft (lights, cruise, and wiper), and disconnecting the dash harness from the body harness. In my 86 I had four plugs by the drivers side, and three by the passangers side.

Step #2
Remove the stereo and unplug it from the dash harness, there should only be like two plugs.

Step #3
Remove the dash from your car per instructions in the FSM. I lost count of how many screws are on there, but there are quite a few. Don’t be like me and end up with more screws than you remember taking out.

Step #4
Once you have the dash out of the car and on the ground, you will have a good view of the dash harness. Remove the cluster (both the combo meters and volt/pressure) from the dash. Now, you can label the connectors so you can know where they go or you can leave them plugged in. Now comes the FUN part…

Step #5-A
On your stock harness, there should be 3 big connectors and 1 small four wire connector that plug into the main cluster. Find the wiring diagram for the combo meter/main cluster for both your car and the donor gauges. On my car, the 3 big connectors control the illumination for the idiot lights, instrument lighting, etc. The small 4 wire plug is for the tachometer.

Notice the 87 cluster has a 4-wire plug coming out of it. This plug is not needed, since it is for the o2 sensor light.
Leave the stock connectors plugged in (plug them back in if you labeled them) their stock locations so you know where they go. Match each of the three big main cluster connectors from both harnesses (my 86 had two black and one white, where the 87 had two white and one black).

Cut the three pigtails off the 87 harness (leave enough wiring to solder), and plug them into their normal location if you removed them. Separate the wires as good as you can, so that you have room to solder. Now would be a good time to cut strips of heat shrink tubing and slide it over the wiring, that way you don’t forget or realize it when it’s too late (don’t ask).

Step #5-B
Now, once you find each of the wires and matched them to the wires on your harness, look at your pigtails and sort out which wires go where. I recommend you follow this: cut the wires ONE by ONE from the old harness leaving enough wire to splice with your new pigtails. Match them up to the corresponding colors/wires on the pigtails and check the FSM wiring diagrams to make sure each wire goes in the correct location. Most of the colors are the same, but there are a few that aren’t and also some locations are different. This isn’t a problem, but if your not paying attention, it can be.

FOR THE TACH: Cut the plug off your stock harness and look at these wires: black, yellow, and green. Find these colors on the 87 pigtails: black or pin 20, yellow or pin 17, and green or pin 3. Put them together, black and black, yellow and yellow, and green and green.

FOR THE SPEEDOMETER: On the 87 pigtails It was the red white wire that plugs into the main cluster. This wire feeds the signal to the speedometer on the cluster. Leave this one alone for now, as you will need it later (you’ll see).
Once you have them all together, solder and heat shrink wrap them (except the red/white wire on the pigtail), and plug them back into their locations.

On the sub gauges (volt/oil pressure), there is only one connector to these gauges. On my 86 I didn’t have to change the sub gauge connector as it was the same as the 87. It should plug right in, and work as it is the same. Consult the combination wiring diagram and pinout in the FSM to make sure they are the same.

Step #6
Next you have to wire in the speed sensor.

NOTE: I’m assuming that the speed sensors are matched with the rear end of the vehicle, as I read that somewhere before and also stated that at the beginning of this guide. I had replaced my transmission with one from an 88, and also kept the speed sensor. I’ve measured the speed at which I’m traveling and the speedometer reading with a GPS to determine how far off it was. Mine is off by 1.5mph, plus or minus .5 mph.

Now take your old gear out and slide the new one in. This worked on my friends T-5 transmission with a 71C sensor, so im damn sure it’ll work on the 71C with the cable type sensor. Now your going to run the power/signal wire from the sensor to the cluster pigtail.

Remember that red/white wire you left alone? Now that one you use for the signal to the speedometer. Get a long enough wire and solder one end to the red/white on the cluster, while running the other end to the sensor. Solder it to the signal wire from the speed sensor to it.

Next find a place with a good solid/clean ground and run the ground wire for the speed sensor (black wire coming off the sensor) to that.

…And you’re done!

Now put everything back together, and take the car for a test drive to make sure the speedo is working as it should. As stated above, the only issue I noticed was the water temp gauge taking some time to get up to the correct reading. I don’t mind this, as I have an aftermarket one which I’m going to use anyways :-D.