Dipped headlight not working even after replacing it

witnessmenow

Hello,

I have an Astra H Estate and the drivers side dipped headlight (H7) went, I went to replace it today with a couple of bulbs I had already had, they looked ok but didn't work, so I assumed bad bulbs (or I had put the bad ones back or something stupid).

Went and got a new one from the motor factors and it doesn't work either.

A couple of things I've tried in an attempt to figure out what's up:

• New bulb has continuity so it would indicate it's fine. (so does one of the original spare bulbs I had)
• I've measured the voltage on the bulb connector in the car and measured 11.5V or so, while a small bit low side (my multimeter is also fairly crap) but seeing as my car is starting fine I doubt its a battery thing.

So I'm kind of stumped, any idea what it could be or what else I could test? The connector looks OK physically.

colm_mcm

Have you got a good earth?

witnessmenow

colm_mcm wrote: »

Have you got a good earth?

Cheers for the reply, To be honest I'm not sure how to check that!

All other bulbs in the same fitting are working so I would assume its OK, but I don't know that for sure. Any advise on how to check?

Dayo93

Maybe the bulb is not making good contact in the holder had this on our 2006 Astra earlier in the year , the connectors in the bulb holder were a bit loose a little adjustment with screwdriver and no more issues

dePeatrick

Connectors can get corroded too, stick a torch in there and get a good look.

smuggler.ie

Could it be connectors in the block worn/corroded - one of them not making connection.

witnessmenow

Ok so more updates

Went at it again this morning, it does show 11.4v when the lights are on, but strangely it shows 11.5v when the lights are off, so I'm now thinking it's not a connection or a bulb thing.

Brought it into a local place there today and said the connections were all fine and they think it's been disabled by the ECU or something and I might need to take it to Opel.

I actually do have the opcom unit from when I got the car (I enabled cruise control with it), no idea does it still work but any ideas on what to look at in that? Not sure the car is worth bringing it to Opel 😅

kirving

11.4V with lights on wouldn't be unusual necessarily. The load of the other lights being on will cause a voltage drop on the circuit.

My previous car controlled current to the side lights via the ECU. A short in the boot wiring harness caused the front right sidelight(and right rear) to flash 10 times and consecutively lower brightness before cutting out.

Turns out the ECU was limiting current as it sensed the short.

A diagnostic by Opel dealer may be cheaper than an Indy messing about for a few hours.

smuggler.ie

I read somewhere that : removing bulb, then locking car for an hour, then installing bulb, somehow resets ECU.
Don't take my word for it, but cost nothing to try.

corks finest

Dayo93 wrote: »

Maybe the bulb is not making good contact in the holder had this on our 2006 Astra earlier in the year , the connectors in the bulb holder were a bit loose a little adjustment with screwdriver and no more issues

Just what I was thinking,scrape it a bit

witnessmenow

Apparently it was a blown "UEC" (?), being sorted today. Thank you for the suggestions.

colm_mcm

witnessmenow wrote: »

Apparently it was a blown "UEC" (?), being sorted today. Thank you for the suggestions.

https://youtu.be/J8DOnb4bckA