Griffith headlamp wiring fault
Discussion
Hello to all, first post here although I have read and learned a lot from this forum over recent months. I've had my Griffith for a bit over a year now though haven't used it as much as I'd like. I'm determined to fix that this year!
Anyhow, I have a wiring issue with the dipped headlamps. I was away last week and a couple of times used the lights but found the dipped lamps would not illuminate. Switching to main was fine, they worked. After a couple of minutes, the dip lamps came on and I was able to complete my journey without further problems. Next evening - same thing happened again. Now back home, the dip beam does not come on at all.
Prior to this, they had always worked as they should. I've now opened up the steering column enclosure and I have about 12V entering the dip switch (blue wire) and in both dip and main beam positions, the dip wire (blue/red) has about 12V. So all looks OK at the dipswitch.
Fuse 5 is for dipped headlamps. Between this fuse and the left headlamp there is a pretty good connection, but between fuse and dipswitch, I have over 80 ohms resistance. So I think it's likely to be a corroded or burnt connector somewhere in the wire behind the dash, between dipswitch and fuse panel. The question is, where? The fuse itself looks clean.
I can't see the cable route at all. I assume it runs from the dipswitch behind the dash to the left side footwell. Can anyone confirm whether there is a connector in the blue/red wire between dipswitch and fuse panel? Is this going to be a dash-out job? How difficult is it to get the fuse panel out to have a look behind it?
Anyhow, I have a wiring issue with the dipped headlamps. I was away last week and a couple of times used the lights but found the dipped lamps would not illuminate. Switching to main was fine, they worked. After a couple of minutes, the dip lamps came on and I was able to complete my journey without further problems. Next evening - same thing happened again. Now back home, the dip beam does not come on at all.
Prior to this, they had always worked as they should. I've now opened up the steering column enclosure and I have about 12V entering the dip switch (blue wire) and in both dip and main beam positions, the dip wire (blue/red) has about 12V. So all looks OK at the dipswitch.
Fuse 5 is for dipped headlamps. Between this fuse and the left headlamp there is a pretty good connection, but between fuse and dipswitch, I have over 80 ohms resistance. So I think it's likely to be a corroded or burnt connector somewhere in the wire behind the dash, between dipswitch and fuse panel. The question is, where? The fuse itself looks clean.
I can't see the cable route at all. I assume it runs from the dipswitch behind the dash to the left side footwell. Can anyone confirm whether there is a connector in the blue/red wire between dipswitch and fuse panel? Is this going to be a dash-out job? How difficult is it to get the fuse panel out to have a look behind it?
Thank you for that information - I bet that was a job to find! Good to know for future.
I got some time over the weekend to look properly and discovered (contrary to what I'd understood) that actually TVR DID fit relays to both the main and dip beam circuits; on my 500 they are relays 11 and 2 respectively in the passenger footwell fuse/relay panel. Suddenly it all became clear.
The 80 ohms I measured the other night was not a corroded connection between dipswitch and dipped beam fuse 5 - it was actually the dipped relay coil resistance, with the circuit completed via earth and sidelights back to the positive side of the fuse.
The actual fault preventing my dipped beam operating, was burnt points in the relay. Swapping the relay for another has fixed the problem. I've checked current draw to be confident there's not a fault in the circuit, so I presume the contact points have just sooted-up after twenty-odd years of use.
As a side note, the wiring diagram in the Bible (p271) shows none of this. It shows the wiring from headlamps to a connector, labelled 'Block E', but there is no information as to what is connected on the other side of Block E. The same is true of many similar connectors on the diagram. Does anyone have wiring information for any of these Blocks (including the dashboard) that would help lift the mystery?
I got some time over the weekend to look properly and discovered (contrary to what I'd understood) that actually TVR DID fit relays to both the main and dip beam circuits; on my 500 they are relays 11 and 2 respectively in the passenger footwell fuse/relay panel. Suddenly it all became clear.
The 80 ohms I measured the other night was not a corroded connection between dipswitch and dipped beam fuse 5 - it was actually the dipped relay coil resistance, with the circuit completed via earth and sidelights back to the positive side of the fuse.
The actual fault preventing my dipped beam operating, was burnt points in the relay. Swapping the relay for another has fixed the problem. I've checked current draw to be confident there's not a fault in the circuit, so I presume the contact points have just sooted-up after twenty-odd years of use.
As a side note, the wiring diagram in the Bible (p271) shows none of this. It shows the wiring from headlamps to a connector, labelled 'Block E', but there is no information as to what is connected on the other side of Block E. The same is true of many similar connectors on the diagram. Does anyone have wiring information for any of these Blocks (including the dashboard) that would help lift the mystery?
Austin Seven said:
Thank you for that information - I bet that was a job to find! Good to know for future.
I got some time over the weekend to look properly and discovered (contrary to what I'd understood) that actually TVR DID fit relays to both the main and dip beam circuits; on my 500 they are relays 11 and 2 respectively in the passenger footwell fuse/relay panel. Suddenly it all became clear.
The 80 ohms I measured the other night was not a corroded connection between dipswitch and dipped beam fuse 5 - it was actually the dipped relay coil resistance, with the circuit completed via earth and sidelights back to the positive side of the fuse.
The actual fault preventing my dipped beam operating, was burnt points in the relay. Swapping the relay for another has fixed the problem. I've checked current draw to be confident there's not a fault in the circuit, so I presume the contact points have just sooted-up after twenty-odd years of use.
As a side note, the wiring diagram in the Bible (p271) shows none of this. It shows the wiring from headlamps to a connector, labelled 'Block E', but there is no information as to what is connected on the other side of Block E. The same is true of many similar connectors on the diagram. Does anyone have wiring information for any of these Blocks (including the dashboard) that would help lift the mystery?
If you take the off side dip and main off the original supply, the near side gain 25w each . Then use two new relays taking their supply from the starter motor , you gain a total of 100w ! I got some time over the weekend to look properly and discovered (contrary to what I'd understood) that actually TVR DID fit relays to both the main and dip beam circuits; on my 500 they are relays 11 and 2 respectively in the passenger footwell fuse/relay panel. Suddenly it all became clear.
The 80 ohms I measured the other night was not a corroded connection between dipswitch and dipped beam fuse 5 - it was actually the dipped relay coil resistance, with the circuit completed via earth and sidelights back to the positive side of the fuse.
The actual fault preventing my dipped beam operating, was burnt points in the relay. Swapping the relay for another has fixed the problem. I've checked current draw to be confident there's not a fault in the circuit, so I presume the contact points have just sooted-up after twenty-odd years of use.
As a side note, the wiring diagram in the Bible (p271) shows none of this. It shows the wiring from headlamps to a connector, labelled 'Block E', but there is no information as to what is connected on the other side of Block E. The same is true of many similar connectors on the diagram. Does anyone have wiring information for any of these Blocks (including the dashboard) that would help lift the mystery?
Yes, David, I plan to do just that with the dipped beam, although so far I have been quite satisfied with the main - it's so much better than the dip. Maybe I'm not driving fast enough!
The other thing I'm doing once I've got the relay installed is fitting Philips +130% bulbs and, even more important by the looks of it, is carefully attempting to clean the inside of the headlamp glass. I read about someone doing this with cotton wool dipped in isopropyl aclohol, gripped in a piece of bent wire. It doesn't look very easy, but we'll see. Just need to make sure I don't push too hard and pop the lamp unit into the pod . . .
The other thing I'm doing once I've got the relay installed is fitting Philips +130% bulbs and, even more important by the looks of it, is carefully attempting to clean the inside of the headlamp glass. I read about someone doing this with cotton wool dipped in isopropyl aclohol, gripped in a piece of bent wire. It doesn't look very easy, but we'll see. Just need to make sure I don't push too hard and pop the lamp unit into the pod . . .
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