Wiring harness for an 87

[noid]

Looks like the 87 c101 cars/connectors do not have pins:

8 fuel rate dme

9 tach dme

14 Vehicle speed dme

15 K5 Unloader relay

Both 87 cars I have checked do not have these pins. What is the procedure for the x20 - C101 wiring harness for these pins?

[Jean]

Just like with any swap, such as more common 24v swaps, run the wires from the engine harness to the car / cluster.

[noid]

That much I figured. Was just trying to see where exactly you guys spliced in.

For example on an 89+ the DME engine speed (pin 9) goes directly through c101. In contrast, in a 87 it goes through c1 (im guessing that is the actual cluster plug), c103, c104 and c235. So where exactly along that path have you guys spliced in?

[Jean]

Under the dash, there is a connector by the glove box area. It's pretty simple, match the wires by function.

[noid]

I am pretty sure you are talking about c104:



That which would be pin 9 on c101 for 89+ is pin 1 on c104 on a 87'.

What would be pin 8 on c101 for 89+ is pin 3 on c104 on a 87', and can similarly be found on c103, c104 and c235.


The real two tough ones to figure out are 14 and 15:

On an 89 the wire goes to the K5 unloader relay:


It looks like there is no wire going to the K5 unloader relay on an 87:


Does that mean on an 87 pin 15 can be ignored and eliminated?


I cant find c101 pin 14 in the electrical diagrams (I am sure its in there, i just cant find it). Whats the process for this pin?

[noid]

Did more research looks like for pin 14, you just need to splice pin 14 from the engine side (X20) into brown/red wire that comes off the yellow plug (c3) of the cluster (pin 26 on the yellow connector).

That still leaves pin 15 as noted above? Should pin 15 be ignored and eliminated or?

[noid]

Put this together today: Still need someone to confirm pin 15.

[JGood]

Regarding the unloader relay, looks like power goes through the ignition switch, and when in the "start" position, power goes to the unloader relay coil (energizing the relay, cutting power to windows and other accessories), then to the c101, then to the starter, in the form of the common green/black starter wire. In your first diagram, it goes through pin 15. In the 2nd, pin 18.

Yes, the c104 contains 3 wires. Can't remember off the top of my head which is which, but if you look for e36/e34 schematics for the x20, you can match them by function. One is tach signal, one is OBC MPG signal, I think the other is the code function? Which most people don't use. I think that's pin 2 (middle)

You also need the speed signal from the cluster to the appropriate x20 pin. I'm not sure why'd you'd tap into the cluster/OBC wiring for that, you can just grab the signal from any of the empty pins on the back of the cluster in the green connector.

[noid]

As noted in my excel spread sheet its pins 1 and 3 on c104. Pin 1 (Black wire) is for Tach, and Pin 3 (White/yellow wire) is for fuel consumption.

The green connector is a great suggestion! Although, some clusters did not come with this green connector, so its still worth mentioning that the signal can be had from the yellow connector.

The question of pin 15 still remains, because on an 87 its a common wire like you said through pin 18, does that mean pin 15 AND pin 18 (x20) are both wired into pin 18 (c101) or is pin 18 (x20) only wired to pin 18 (c101) and pin 15 is eliminated. I am guessing the latter?