Forgot to add Measure voltages with light off and on, a dropping voltage (with light on) will indicate where the problem is (poor connection dropping voltage under load)
Thanks Let me work back through the feed , from the switch to fuse holder and see if I can find the point the voltage is dropping off , there s 2 relays in there too Battery is happy at 13.48v Nearly 1 volt is being lost before it even reaches the bulb The bulb is only seeing 12.5v instead of 13.48v 55w bulb at 12.5v draws approximately 4.4 amps 0.98v drop at 4.4 amps = 0.22 ohms resistance in the feed wire
I am sure you will get there As a rule I tend to “start in the middle of the cct”, this cuts the problem in half
Next steps ? Run a jump wire from relay pin 87 directly to bulb connector positive pin — bypasses switch and all wiring between relay and bulb in one go. Voltage jumps to 13.4v+ → fault is in that wiring Voltage stays at 12.5v → fault is on the feed side before the relay
Just as a check run a wire from the battery positive direct to the bulb +ve connector and check the voltage, with and without the engine running. That bypasses everything.
You’re doing fantastically iirc first position is dipped beam, the left hand headlight, second position is main beam, the right hand headlight. When the headlight flash is used it causes both to illuminate. It’s awhile since I had one to check though.
first position is dipped beam (two middle w5w bulbs), the left hand headlight, second position is main beam H3 + 2 w5w bulbs, the right hand headlight, full beam button or the quick flash, H1 bulb, h3 bulb and the 2 w5w bulbs
Very thorough! What state is the barrel connector in? I've had issues with some pins not engaging enough, may be some corrosion in there.
Are you all talking about the light switch on a 748? The first position is sidelights The second and last position is dipped beam To get the main beam there is a push button above the light switch
At least you’ve now proven it’s definitely to do with the wiring and nothing to do with the headlight itself. It’s just an iterative process now to check every step of the circuit until the part causing the resistance is identified. Using the same clean & new cable, used for the direct from battery to main beam test, leave it attached to the main beam +ve and run it back to various points in the +ve feed to the bulb. NB assuming you didn’t have a new clean path on the -ve side of the main beam at the same time as testing for any voltage drop direct from battery to bulb you can discount the earth side of the circuit as the culprit.
Direct battery to bulb test I used a new cable for both -ve and +ve main beam , connected directly to the battery -ve and +ve Other Tests prior Main beam on , new cable for -ve to battery directly , use existing loom +ve Result: 12.5v Main beam on , new cable for +ve to battery directly, use existing loom -ve Result: 13.2v Definitely the +ve wire to the main beam bulb Does anybody know how this disconnect , any trick ? Normally with quick connects its a twist to unlock , I do not want to damage it
I can sympathise because they can get quite stuck up if not removed for a long time. It's like a rapid spiral unscrew so the effort is almost slightly upwards as well as revolving, and I've had to resort to soft jaw pliers on the steel thimble before now
Thanks Chris , I left it be , I had the jaw pilers out but taught better of it I took off the Fuse box , it is a bit manky behind there , cleaned with contact cleaner Engine idling , 13.8V displayed on the Bike display (Translogic) Main beam on , -ve to battery directly , use existing loom +ve Result: 13.82v (Multimeter) Main beam on , -ve to Headlight directly , use existing loom +ve Result: 13.82v (Multimeter) 13.8V displayed on the Bike display (Translogic) Engine idling -- > Bulb connected New Philips 55w bulb , dielectric grease , contact cleaned Main beam on ,Bulb on , voltage drops to 12.5V!! on the Bike display (Translogic) Tested again , disconnected bulb , Main beam on , -ve to Headlight directly , use existing loom +ve Result: 13.82v (Multimeter) Tested the Full beam , it was pulling it down to 11.2V , Now at 12.5V Any ideas?
I am guessing feed to translogic is same as feed to bulb Don’t have a cct diagram myself I would be looking at the diagram to find feeds to bulb and translogic, as that’s where there issue appears to lie
Agree with comments above,I think that you are doing well for someone with limited electrical experience
Before it was Main beam on , -ve to Headlight directly , use existing loom +ve Result: 12.5v (Multimeter) After fuse box clean Main beam on , -ve to Headlight directly , use existing loom +ve Result: 13.82v (Multimeter) Bulb connected it's 12.5v
Ok it’s not obvious where the translogic gets its feed from I would place a feed direct from battery to fuse c (output) check voltage at bulb Depending on result this rules out/in lighting cct
