How to Install a Digifant Wiring Harness on a 2.1l Vanagon.
I usually just remove the old harness one plug at a time and plug in the new harness this way. I have done it many times, and since there is really only one place for the wiring to go and fully reach it is usually a no-brainer. However, just in case you have questions here is how I would do it:
Unhook ground terminal on main battery under passenger seat.
Open rear seat, remove the 10mm plastic nut below the metal ECU cover. Pick up the cover from the bottom and little and push straight up on it until the white plastic holders become disengaged with the floor of the van. Flip the ECU cover over. You will see the ECU and a brown wire going to a stud. Unplug the ECU by flipping the metal tab out of the way a little, and undo the nut on the stud to release the brown wire with the ring terminal. Go to the driver’s side rear wheel well and look at the bottom side of the floor in the area of the ECU. You should see the harness coming through the floor. Give it a pull and the rubber grommet should pull free from the floor and the ECU plug can be threaded out of the hole along with the brown wire. Follow the old harness along the frame cutting tie wraps as you go until you get to the engine bay. Thread the harness through the firewall into the engine bay. It should come through on the right side of the thermostat housing.
Get the new harness. Go to the engine bay. Thread the new harness ECU plug from the area to the right of the thermostat housing, through the firewall, along the frame as the old one was and Thread the ECU plug and new brown wire through the hole. Seat the grommet. Install the brown wire on the stud. I would wait to install the ECU on the harness until everything else is hooked up. Tie wrap the new harness as the old one was to the frame.
In the engine bay next to the thermostat housing the wiring harness splits. One side goes to the left to two harnesses. One is a green plug all by itself. This replaces the blue plug that plugs into the Temp II sensor which is located on the thermostat housing (usually pointing to the left side). Unplug the temp II sensor from the old harness and plug in the new one.
Brown Wires with Ring Terminals- If you continue on that left side the harness it will split into some individual wires and some sub harnesses. The individual wires, the brown ones with ring terminals on them are for the ground connections that are on the firewall near the coil. Unscrew the 10mm bolt that holds the old brown wires in place and install the new ones. If the grounds need to be cleaned please do that at this time with some sand paper.
Green Wire- The other individual wires are a green wire that goes to the coil. If you don’t have a tach then simply unplug the old single green wire from the coil and plug in the new one. However if you do have a tachometer (RPM Meter). The old coil wiring should have a double plastic plug here with two green wires in it. One of them goes to your new harness and the other goes to a harness that you aren’t replacing. Since you have been unplugging as you go, pull on your old harness to see which green wire one will go with your old harness. Unplug the double connector from the top set of wiring from the coil. The wire that goes to your old engine harness you need to remove from the plastic connector. You can do this by taking a small flat blade screwdriver, going in the end that plugs into the coil. You will see a small notch in the center of the plug as you look at it from the end. Put the small screwdriver in that notch and give a small pry. It will release that metal plug. Then you can simply push in the new plug from the back side of the white double connector. Now plug the connector back onto the coil making sure that both sides seat properly.
Small Black wire- Another wire in this area is small black wire with a plastic connector on the end. This wire goes to the coil on the lower side where there is also another black wire. Just unplug the one that goes with the old harness and plug in the new one.
There harness should split into three short sub harnesses here.
One goes to the relay box above the coil. That is very obvious because it has relay mounts on it. Open the box, remove the relays (note which goes on which side of they are different), remove two small clips that hold the relay mounts to the inside of the box, remove the relay mounts and pull up on the plug on the side of the box to remove it as well. Install new wiring here as the old was installed. Plug the relays back in the proper position.
Another short harness here goes to the oxygen sensor. The old wiring is a large green wire and a fuel injection style plug together on this harness. Trace the wiring from the oxygen sensor which is screwed into the catalytic converter, to where it plugs in to the old harness. Unplug it. Now look on the new harness for that same combination of a single spade plug and a single fuel injector style connector on the sub harness. The single wire os white and the fuel injection style plug wiring is red and brown. Plug those two wires in.
The only part of the harness left on this side of the engine bay should be a section with two fuel injection style plugs that have a white wire and a red and white wire, and a single skinny wire that should be white with a green stripe and have a plastic connector on the end. The two fuel injection style plugs are for the fuel injectors on the driver’s side (left). It doesn’t matter which is which. They are all pulsed at the same time. The single white wire with the green stripe goes up to plug into the wiring for the AC compressor. If you don’t have AC, then don’t worry about it. It will just not plug into anything.
Now lets move on to the right side of the engine bay and continue to trace the old wiring harness from the right side of the thermostat housing along the rear firewall, over to the right side of the engine bay.
Directly to the right of the thermostat housing there should be some single wire plugs that are just plugged together. Don’t worry about these. They need to stay plugged together, but they don’t plug into anything else.
Hall Sender plug and ground- Also there is a sub harness that comes out of here that has a wire that ends in a three prong plug and a single brown wire with a ring terminal on it. That needs to thread under the intake to the distributor. If you look on the left side of the distributor you will see the plug for that. Push in on the wire and release the plug. Pull it straight up while pushing on the retaining wire to unplug it. The brown wire with the ring terminal grounds to the top of the cylinder head on the driver’s side underneath of where the AC compressor normally is. There should also be a ground strap going from this location to the firewall near the coil where you installed those other single brown wires with ring terminals. Be sure this ground strap is there, and if it isn’t, buy a new one and install it. Grounds are very critical to the proper operation of your engine. So clean up the ground location with a piece of sand paper, install the new brown ring terminal there while also being sure that the ground strap is installed on the same 10mm head bolt. Then plug in the new three pronged plug for the hall sender on the side of the distributor.
Air Flow Meter- Following the harness to the right it is going to split again. One of the wide plugs is for the air flow meter. It has five prongs but only four are used. I would remove the air box while installing this harness as you need it to be out of the way. Just note that the Air Flow Meter wiring is here when you go to reinstall the air box, be sure to plug it in.
Fuel pump plug- The same area the air flow meter plug comes out of the harness you should also see a Red with a White stripe wire and a brown with a green stripe. The Red with a white stripe is power for the fuel pump and the brown with the green is the ground for the fuel pump. Some early harnesses have just a single power wire here. It should be coming through the firewall behind where the air box should normally be. If you just have the single wire, then just plug the red wire into that and you are good to go. If you have the two wire plug (T shaped) then install the two wires in the plug provided the same way they are installed in the old harness and plug this in. We supply them not installed because some folks have the single and some have the double.
Power Steering Plugs, etc.- The harness splits again and the next set of plugs we come to are two 90 degree spade plugs that plug into the switch on the power steering pump. You can plug into either as it doesn’t matter. There is a single fuel injection style plug that is for the throttle position switch. Simply look at the throttle, you will see some wiring coming out of the bottom and look on the right intake running on the top. It is a white plug there.
The final wire that comes out of the bunch is a three prong plug with a longer piece of wiring on it. This goes to the idle control unit on the top of the center of the engine. Simply trace the old harness to this, unplug it, and plug in the new.
Right Side Fuel injectors- trace further and you will come to two fuel injection style plugs with white and white and red wires. These are for the two fuel injectors on the right side of the engine bay.
Idle Control Unit- If you keep tracing to the end of the harness you will see a large plug that looks like a double relay plug. This is for the Idle Stabilizer Control until which looks like a large relay. It is located behind the passenger side rear tail light. Remove the four phillips head screws and remove the rear tail light. Look straight in with a flash light and you will see it on the firewall. Pull straight up on the unit and plug and it will come loose from the mount on the firewall. Thread the wiring out of this location and unplug the ISCU. I usually use a small screwdriver to pry this carefully free of the plug. Now plug the ISCU into the new wiring harness end and thread this back through the opening in the engine bay, passed the plastic wall that separates it from the area behind the tail light and install the ISCU back on its plastic mount by lining it up and pushing down until it locks into place. Reinstall the rear tail light.
At this point your new harness should be fully installed with no left over wires. If you unplugged the old as you went it should be free and you can get it ready to come back to me as a core. Use tie wraps to secure the new harness anywhere it could chafe or hit against objects like the throttle cable, etc. Plug in the new ECU into the harness and put the cover back into place. Hook your battery ground back up. You should be ready to start up your van.
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