Adding a headlight switch relay |
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by Ken Lewis
Background
The stock Vanagon headlights are woefully weak, and many owners decide to upgrade to more powerful solutions. A common replacement are the Hella H4 european-style headlights. Unfortunately, a more powerful headlight draws more power, and the stock Vanagon switch can't handle the increased current. It took a headlight switch melt down to motivate me to find a better solution.
I did a good bit of research and came up with a method that has these benefits:
- 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.
- None of the original wires are cut.
- All of the original HI and LO beam fuses are still used.
- A noticeable gain in light output.
- My headlites used to dim when I turned on the heater fan. Not any more!
- It's SANO i.e easy to install (or return to OEM) and well concealed.
Note: My vehicle is an 86 crew cab so I reference that schematic in the Bentley. Parts list
You will need the following:
- Two (2) automotive-type relays. I purchased mine at Radio Shack. They are rated at 30 amps with four push on male, spade terminals. Physically these are black plastic cubes, about 1 inch to a side, with a mounting tab.
- 10-gauge wire, the length depends on how you route it from the positive battery post.
- Some 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.
- 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.
- A copy of the Bentley manual (Official Volkswagen Repair Manual: 80-92 VW Vanagon, incl Camper, Diesel & Syncro, available from several of the vanagon.com featured vendors.)
Procedure
Reference page 97.78 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 contacts. The female connector already on the wire will fit the relay terminal. The other relay contact 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 I think few Vanagons have the same floor board between the front seat like my Crewcab. Be careful of high traffic areas or chafing through holes.
Summary
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 $43 from VW.
I do not know if the round headlight vans have the switch failure problem, but you will achieve a voltage (and current) gain at the lights by following the process I outline below. This is a must if your are doing any kind of headlight upgrade. Measuring at the fuses I found that I was able to gain 1.5 volts on the low beams and 2.5 volts on the HI beams.
A proper crimper greatly enhances things. The Shack also sells these.
Drive Safely & Good Luck,
Ken LewisSee also
Independent Wiring for Headlamps
(specific to Vanagons)
