Repinning your harness to put an LA3 into a Merkur

There are more detailed, complete instructions at Merkurencyclopedia.com. 

These are the pins that you have to move to put an LA3 into your Merkur:
1. Pull out pin 43 and move it to pin 27. This connects the VAF signal. 

2. Pull out pin 25 and move it to pin 43. This connects the VAT signal. 

3. Pull out pin 32 and move it to pin 31. This connects the boost controller. 

4. Pull out pin 35 and insert it into pin 33. This connects the EGR solenoid signal. 

5. Put a spare pin into number 24 and run it to Signal Ground which is pin 46 for permanent premium mode. Or install a switch so that you can switch between premium and regular modes.

You don't need to hook up an Air Charge Temperature (ACT) sensor. You don't need to hook up the Brake On/Off (BOO) switch. And you don't need to do anything to keep the cruise control working. The cruise is a completely separate system from the EEC-IV in a Merkur. No modifications necessary.