Gremlin Posted June 4, 2013 Share Posted June 4, 2013 Ok got one for your collective brains......... but first a bit of a background of the system and vehicle............its going to a bit long..... So i have a series 3, been evolving over the years, during my last rebuild, i went with a defender tdi200 bulkhead and electrics. So i had the task of maatching series bits to later defender electrics. Mainly one of series things that needed matching to the defender system was the fuel gauge to sender. I used a series sender (brand new at rebuild) as i still run the series tank, the gauge is a defender unit, i managed to match approx the gauge to the sender by adjusting the float in the tank. I was lucky that the resistance was nearly the same for the sender. One glitch was that my series had a low fuel warning lamp, while the defender electrics did not. So i wired one up accordingly, and functioned brilliantly for the last couple of years. Now ffwd to this month, this darn bulb started coming on faintly constantly, only going bright when the level is low. Now the problem seems to be increasing and there is little or no difference in the brightness making it practically useless as a warning light. So i got busy and got into the sender hoping to find the cause. Found nothing!! i even opened up the sender to have looksee, nothing seemed out of place. Put it back in and the problem fixed itself........, i was pleased i had solved the problem!!! very happy bunny...................i was good for a few meters, as soon as i got out the garge the problem came back. Check all the wiring on the loom and its all good. I went to this process for the last 2 weekends trying to solve the issue with little or no succsess. From what i can figure out there seems to be a leakage to earth within the sender making the bulb dim! So any bright sparks out there have an idea how the F to fix it......as this one just beat me. (i know a new sender would solve it, so that will not work as a fix, just as a last resort.......) Appriciate some help........... G Quote Link to comment Share on other sites More sharing options...
snailracer Posted June 4, 2013 Share Posted June 4, 2013 Take it out and stick a continuity tester on it. Go round all the possible points where it could be earthing. My guess would be somewhere around where the terminals go through the plate. Have you tried running wires bypassing the loom to eliminate any chafing of insulation? Probably would be easier to get a new one... Quote Link to comment Share on other sites More sharing options...
Gremlin Posted June 5, 2013 Author Share Posted June 5, 2013 My last try, i rigged the circuit on the bench, at first it was the same, dim bulb, then i bypassed the wire from the wiper box to the terminal, and it sorted itself out for a while. Then i reconnected to the terminal and the problem was gone. Fitted it back in the car and bingo, it came back! I have a suspect that the short wire from the wiper box to the terminal is some how leaking to earth, Is diesel conductive??? next remedy is changing that little bit of soldered wire............ My sole reason for not replacing it is the gauge works perfectly. to stop the annoying bulb all i need is to remove the wire from the terminal at the sender, thus eliminating the warning (not really a solution) G Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 5, 2013 Share Posted June 5, 2013 The fault must be in the sender - you have proven the wiring is fine by disconnecting it from the sender and finding the bulb stays out. I don't think diesel is very conductive, but I'm pretty sure it does help reduce the resistance within the sender. Regardless, the warning light circuit is not behaving correctly, and would work the same way irrespective of the gauge used because that is on a separate, parallel circuit. I didn't bother with a warning light when I converted my 109 to diesel - I use the space in the dash for an alternator warning light as the instrument cluster has an oil temperature gauge as well as the two standard gauges (MoD style), so my original charge light was ousted. If you're determined to have the fuel warning light, I'd look into whether it should have another component in the circuit to step the voltage, like a resistor, transistor or capacitor. If not, then I'd suspect a worn out sender - it could be that a resistive coating on a winding or area of contacts in the sender has worn away, allowing a restricted current across when it should be isolated. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.