Jun 24

Strange 9004 wiring issue.

I have a pair of Morimoto H1 6.0 retrofitted into the stock lamps of my 1994 Volvo 940 and using a TRS 9007/9004 relay harness and TRS H1 bulbs.

(my retrofit)

They have been working great until recently the passenger side just won't activate.

Here's where it gets strange, so bear with me.

I've tested that lamp (R) on the driver's side (L) ballast and it works, so the bulb is good.

I tested the (R) ballast for 12V and it's getting 12v.

I swap out the (R) ballast for a good one and still nothing.

I again test the (R) for 12v and it's good.

I take the original ballast from the (R) and swap it for the (L) ballast.

Lamps work (both of them). (connected them one at a time to the (R) ballast that's connected to the (L) 12v source)

So, the (R) ballast works.

I put the (R) ballast back on the right side and reconnect. Reconnect the lamp and.... Nothing.

So It's getting 12v, the (R) ballast works when connected to the relay on the driver's side, but not when connected to the 12v feed on the (R) side.

I've checked grounds and they are all good. I even replace questionable points.

Anyone have any thoughts what's going on? Ballast works, it's getting 12 volts, But the known good H1 bulb won't come on.

I'm using an older TRS relay. Is there a possibility that while the relay is sending 12 volts, it's not supplying enough start up amps?