This is the main Digifant fuel injection wiring harness and not the wiring harness for the sensors in the engine compartment for the MV engine code. There were several variations in the MV engine wiring harness over the years. This harness matches the 1990-1991 harness, considered the best by many. The changes were primarily related to the power relays and the ground connections. The 1990-1991 harness used one of the power relays to power the ECU only. The earlier versions shared that relay with some other powered connections. One modification we made with this harness was to add an in-line 5A fuse to the power steering pressure switch connection. The lack of this fuse could cause severe damage with burned and shorted wires inside the harness whenever this 12V wire to the pressure switch either broke or became disconnected and shorted out against a metal part of the engine.

This harness includes two waterproof power relays. Some of the original harnesses from 1988-1990 used a special relay in one position, which is almost impossible to find now. The purpose of this relay was to provide a signal to the ECU for early OBD functionality. Unfortunately, VW never fully added this capability to the Vanagon, so this particular relay serves no useful purpose. This harness will replace all 2.1 MV harnesses from 1986-1991 and includes upgraded power relay connections.

Special note: For 1986 and all Syncro models, there is only a single connector instead of a double connector for the fuel pump. This single wire should be connected to the yellow/red wire in the double-spade connector on the right side engine firewall. The ground can be left disconnected, as the fuel pump ground is near the fuel pump for 1986 2WD and all Syncros with MV engines.

Includes connections to:

ECU

Power steering Sensor

Air Flow Meter

Throttle Switch

Injectors

Temperature Sensor

O2 sensor

Idle Air Control Valve

After the harness has been installed, it should be secured with tie wraps at various places around the engine compartment. Make certain that the ground by the ECU, two grounds by the left firewall, and the O2 ground near the distributor are tightened and have direct contact with bare metal. If there is a problem with any of these grounds, it can cause poor running and be extremely difficult to diagnose.