Bosch H4 headlamp upgrade problem
 

Ordered the Bosch Euro H4 upgrade from our host and thought I would install them on my '89 Targa this morning before turkey time. Things went fine until I tried to connect the plug to the back of the new headlamp assembly. The three prong plug is a different shape on the H4 bulb when compared to the stock H5 headlamps. The stock plug is three prongs in a row "---". The new H4 bulb is three prongs in a C shape "I_I".

I have read the PP technical article on Installing H4 Headlamps and there is no reference to different shape plugs. There is also no reference to plug adapters in the PP parts catalog. Any one here dealt with this problem? PP is closed today (they deserve a day off) so they are not available to help.

Have a nice Thanksgiving everyone!

The 87-89 911's require an adapter that will mate it with the bulb. I bet Pelican carries it
Gary

I doubt that whoever wrote the article ever contemplated the H5/9004 connector to H4/sealed beam connector problem you are presented with!

The real problem is that the male Faston 0.187" connector is not readily available! So, I suggest a bit of improvising, assuming that you have normal hand tools for working with wiring:

1. Get a pair of sealed beam female connectors with pigtail leads.

2. Get a package of at least 10-12 male 1/4" non-insulated Faston connectors. Using your old H5/0994 bulb pins as a reference, trim a 1/4" connector wit 5-6" diagonal cutters ... until it fits in the connector for your H5 headlamps. It may take a few sacrificial attempts to get 6 good connectors.

3. Trim the pigtail leds to your new H4 connector to a convenient length, and strip for attaching your modified Faston connectors. Crimp the trimmed connectors to the pigtails, and then solder them with a good electronics-grade rosin-core solder.

4. Use a multimeter to determine the active pins on your car's H5 connector when high and low beams are switched on. Test heads from battery to your new H4 assemlby can determine which pins are for low beam by looking at the projected beam against a wall or garage door ... and look for the horizontal cutoff. You may want to put some heatshrink tubing over the pigtail and H5 connector after connections are complete on your 'adapter.'

5. Final assembly should be easy ... you may want to make a wiring diagram with the pinouts of the old and new connectors to keep in your glove compartment for future reference!

Good luck!

Warren,

Thanks for your suggestion. Not sure why I need 6 connectors in your step #2? The headlight connector has three female connectors.

Hopefully PP will have a prefab solution for me when they get back from the holidays.

He was probably thinking you'd do both sides...

Silly question, but why did Porsche go to the H-5, since the H-4's worked so well? Yeah...perhaps for the same reason they went from H-1's to H-4's?

Paul,

The H5 assembly is mosly molded plastic, including lens and reflector, and much cheaper to produce! However, it doesn't tolerate higher Wattage bulbs very well, either!

Um...ahem...grunt... well, I'll take those old defangled H-5 units off your hands for you.

I have a SC who was visciously harrassed by the U.S DOT upon her arrival in the America. They made her wear those Damned sealed beam things. Looks hideous.
Our kind and generous DOT has since changed their minds after finding out that the H-4s had been used in a stange, distant continent for 20 years beforehand.:eek:
....let me know ;)

You are welcome to the newfangled H5, once I am successful in getting those pesky electrons from the wiring harness into the H4 bulb. (See above).

Unfortunately, there is only one functional H5. What started this project was an elderly gentleman who ran a red light in front of me. I was able to hit the brakes, but ended up T-boning him at low speed. The end result was one broken H5 lense and a bend front bumper. His insurance will pay. Believe it or not, the insurance is paying me $390 to replace one entire H5 assembly. I was able to buy two H4 assemblies from PP for the same price.