Original Poster: shran

Difficulty: 2 out of 10

Time to install: 30 minutes

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Brief Explanation:

I have not seen this topic covered before, so here goes. If you have an 83-86 truck, chances are, you have the gauge cluster that has either dummy lights or engine gauges on the left side but no tachometer.

I wanted a tach and did not want an aftermarket one since it's just one more thing to mount somewhere, so I snagged a gauge cluster from an '88 Ranger at the junkyard. I soon discovered that it is not a plug-and-play affair, as you may know if you've tried this.

The problem lies in the fact that 83-86 trucks are missing some wiring required to run the tach, specifically the tach signal wire itself. Everything else is there, you just need to repin the green cluster plug and add ONE wire!

I know for sure this works on an '86 with '88 gauges. YMMV. I will not attempt to tell you what color wires you need to move, only what wires go where, as your wiring harness may have different colors than mine (and likely does.)

Tools Needed:

• Philips and torx screwdrivers

• Small flat screwdriver (to remove wire pins)

• Wire cutter/crimper

Parts Needed:

• 1987-1988 Ranger / Bronco II gauge cluster

• One or two extra wires from the brown cluster plug on the donor vehicle (6 inches or so is enough.) Or just clip the whole brown plug from the donor

• 3-4 feet of wire for tach signal

• Crimp on splice connector

• Red butt connector

Step 1:

Remove lower dash trim, ashtray, and gauge bezel. Disconnect speedometer cable, remove (4) gauge cluster mounting screws from the corners of the cluster. Pull it out of the dash, disconnect the two harness plugs from the back. Set old cluster aside.

Next, check all the bulbs in the new cluster. Typically there are some burnt out.

Step 2:

Hold up the GREEN plug, wires facing away from you, observe the top right - there is a chunk of plastic sticking up next to the clip. This prevents you from plugging this into the new cluster. Break it off.

Step 3:

Holding the GREEN plug, wires facing away, observe inside the slotted part that there are clips holding the wires in. Also, notice that on each side of the plug, each wire is numbered 1-18. Wires 1-9 are what we are changing, 10-18 are not important.

Use your flat screwdriver to release the clips while pulling the wires out ONE AT A TIME. Below is the correct sequence for the factory pinout AND the new one - make yours match the new pinout:

NOTE: Note here that PINS 3 AND 4 may be different depending on the gauge cluster you get! It is best to check NOW with the donor vehicle!

Using the extra wire you grabbed with your new cluster, insert this into either pin 3 or pin 4 (MINE WAS PIN 4 - DOUBLE CHECK WITH YOUR DONOR - VERY IMPORTANT!)

Step 4:

Using the length of wire you have, splice into the GREEN side of your ignition coil harness under the hood. Run this wire into the cab and up to the gauge cluster area, and use the butt connector to attach it to the new wire you added to your green plug.

Step 5:

Attach both harness plugs to your new gauge cluster. Start the vehicle, verify that tach is now working. If so, verify that your other gauges are working, reattach speedometer cable, put the dash back together, and you are done.

If it does NOT work, here are some possible causes:

• Spliced in tach wire is not connected to coil, or not connected properly.

• Pins 3/4 reversed.

• Other wiring issue (grounds, loose plug, etc.)

• Tach is simply broken, or cluster is otherwise damaged.

I have a couple additions/options.

First off, before I changed anything I used Shran's writeup and tagged everything with function and both what slot is in now and what slot it needs to be in. It worked great, stupid easy.

And also, when you get done if you had an oil pressure gauge to start with you may find you have an oil pressure warning lamp on.

I was going to but forgot to get pics, you need to swap the oil pressure sender on the engine for an oil pressure switch on the engine itself. The switch is about 1/3 the size of the sender. Motorcraft part #'s SW1311 {#D4AZ9278A, D5AF9278AA} for my 1985. Just get one for your year and engine with a warning light to be safe. Do that and the light goes away.

If you want to keep your original speedometer/odometer it is simple to swap them.

Tools needed:

• 7/32" nutdriver

• 1/4" nutdriver

Time: 15 minutes if you dawdle.

With the cluster removed from the vehicle, first remove the lens and trim from the speedometer pod by removing the three 7/32 head screws.

Then lift off the black surround trim.

That just leaves the gauge itself.

Flip the cluster over and remove the two 1/4" head screws, be ready for it to maybe fall out as you remove the last one.

Then carefully push the gauge pod out of the cluster.

Repeat for other cluster, installation is reverse of disassembly. Both lenses will interchange between the tach and non tach cluster but only the speedometer side trim will (obviously)

And to get the tach to work with engines with different numbers of cylinders you can get modules that change the tach signal to what you need. Dakota Digital makes one, I got one from Baker Electronix... and it doesn't read right, it seems to be 1.5x of what it needs to be.

EDIT: I have tried two clusters and wired directly they read 2x engine speed, somehow they think they are 4-cylinder tachs. I don't have an 87-88 EVTM so how this works with a 6cyl I have no idea. Best bet if you have a V8 is to install the cluster, note how it compares with a different tach (I have been using a digital timing light with the tach function) to see which adapter you need (or not be a tightwad and order the one with 10 options for an extra $10). My module set at 3/4x needs to be swapped with a 1/2x (Baker modules are also reprogramable)

EDIT #2: 1/2 multiplication works great with my V8, best to hook it up and see how far it is off before you order the module though.