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Headlight voltage enhancement relay modification.
I finally got around to doing this mod, unfortunately it took a
headlight switch melt down to motivate me. I do not now if the round
headlight vans have the switch failure problem, but you WILL achieve a
voltage (and current) gain at the lights. This is a must if your are
doing any kind of headlight upgrade. Measuring at the fuses I gained 1.5
volts on the low beams and 2.5 volts on the HI beams.
I did a good bit of research and came up with a method that has these benefits:

I>Greatly reduce the current flow through the pitiful headlight switch.
The switch will now only carry enough current to operate the relays
instead of the 19 amps of high beam current.

II>NONE of the original wires are cut.

III>ALL of the original HI and LO beam fuses are still used.

IV>A noticeable gain in light output.

V>My headlites used to dim when I turned on the heater fan. Not any more!

VI>It's easy to install (or return to OEM) and well concealed.

You will need :
1>Two automotive type relays. I purchased mine at Radio Shack.
They are rated at 30 amps with four push on male,spade terminals.
Physically about one inch black plastic cubes with a mounting tab.
2>Ten gauge wire, the length depends on how you route it from the battery.
3>Some hook-up wire, about three feet (and female spade connectors to
match that wire).It only has to carry enough current to energize the
coils in the relays.
4>A suitable fuse and fuse holder. It will need to be installed at the
battery and feed the ten gauge wire. This is a must.
Reference page 97.78 in the Bentley(My vehicle is an 86 so I reference that schematic
in the Bentley). I pulled off the large White and Yellow wires at 56a and 56b on the
back of the Headlite Flash/Dim Switch. The black plastic cover under the steering wheel
column will need to be removed to access this plug. A large sewing pin or dentist pick
is useful in releasing the wires from the plug.
The two relays can be mounted on the dash board behind the steering
column. They will be nicely concealed by the plastic cover. Mine are mounted
sideways, with terminals facing each other.
Connect the big white wire to one of the relay's spades in the contact circuit.
The female connector already on the wire will fit the relay terminal. The other spade in the
contact circuit is fed by the 10 gauge wire from the battery post. Jumper one of the
coil's terminal to the 56a terminal, the origin of the big white wire. Attach
the coil's other terminal to ground. I used the screw which holds that relay down.
Repeat this procedure for the Yellow wire except feed it with the same 10 gauge
wire from the first one . The relays are right next to each other so make a
small 10 gauge jumper. The second relay's coil is fed by 56b. I did not cover
the route of the ten gauge wire between the relays and the battery. This because
my Crewcab floor board is slightly different than most Vans. Be careful of high traffic
areas or chafing through holes.
This would be a good time to clean up connections at the head lights. Don't forget
to check the ground wire connections or maybe upgrade it.

There are a lot of connections, switch contacts and small wires between
the battery and the headlights. Each drops a small voltage proportional
to the current through it. The higher the current the higher the voltage
loss. This mod reduces parasitic voltage drops to the headlights
significantly. The headlight switch no longer has to carry the headlight
current. A new switch runs from VW.
A proper crimper greatly enhances things. The Shack also sells these.

Check out
for a schematic diagram.
Below is a picture of the mini-fuse block I installed for the headlight upgrade.

Digifant Dynamic oil pressure system explanation.
You have two oil pressure sensing switches.The low pressure switch (4.4) must open between 2.2 and 6.5 psi.
It is located between cylinder 3 and 4The other switch (13.1) must close between 10.9 and 14.8 psi.It is in the vicinity of the oil pump.The flashing LED is associated with the 4.4 sensor.The flashing LED and the buzzer occur with RPM>2000 and no switch closure from the 13.1 sensor.A loose connector in the engine compartment gave me the LED/Buzzer symptom .

Effect on Compression Ratios Using 1.9L Heads on a 2.1L Engine

Compression Ratio equals Total cylinder volume divided by compressed volume.


The Formula:


CR= (CV+HV+X)/(HV+X)




CR=Compression Ratio

CV=Cylinder Volume

HV=Head Volume

X= The rest of the combustion chamber volume including the inverted dome in the piston and the clearance volume.


From the back of the Bentley, page 27 of technical data, the compression ration of the 2.1L is 9.0:1. I used a large plastic syringe I purchased from Advance Auto. Using this I came up with a Head Volume of 16cc for the 2.1L, 12cc for the 1.9L and 50cc for the inverted dome in the piston. The metal head gasket thickness came in at .09cm (6.2cc volume).  For a cylinder displacement I arrived at 527cc (2109cc/4)

            Plugging in the above values and using 16cc for the Head Volume I came up with x=49.875cc(not too far off the amount I measured).

            If we figure the Compression ratio using the 12cc value of the 1.9L heads and using the value of X above, I come up with a compression ratio of 9.5:1.

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Fuseable Link
I have since moved the fusebox from this spot and replaced it with this fuseable link. 

Fusebox and Headlight Relays.
I moved the fusebox here so it is closer to the consumers. The steering column bottom cover is removed so the headlight relays I added can be seen (red arrow).