Fuel Gauge Issue
Discussion
On the basis that it's better to ask in too many places than too few, this query is also on BlatChat, 7-DNA and facebook!
Earlier today I disconnected my fuel gauge to get at some cabling behind the dashboard. Upon reconnection, it read zero.
I have had this happen before and last time, as I wasn't sure how much fuel I had, I decided to fill-up. With the car full, the gauge started working again.
However, I when I did the same, the gauge still said zip.
There are three terminals at the back of gauge. I have 12V and a good earth on two. The other I presume comes from the sender. What should I see on that - a voltage or a resistance (and of what values)? At the moment I have neither.
Is there a way of testing gauge itself to identify whether the problem is there or with the sender/wiring?
Also, is there a fuse associated with these? (all other gauges work OK so I suspect that's not the issue)
If relevant, the car is a 2013 Sigma-engined SuoerSport.
Earlier today I disconnected my fuel gauge to get at some cabling behind the dashboard. Upon reconnection, it read zero.
I have had this happen before and last time, as I wasn't sure how much fuel I had, I decided to fill-up. With the car full, the gauge started working again.
However, I when I did the same, the gauge still said zip.
There are three terminals at the back of gauge. I have 12V and a good earth on two. The other I presume comes from the sender. What should I see on that - a voltage or a resistance (and of what values)? At the moment I have neither.
Is there a way of testing gauge itself to identify whether the problem is there or with the sender/wiring?
Also, is there a fuse associated with these? (all other gauges work OK so I suspect that's not the issue)
If relevant, the car is a 2013 Sigma-engined SuoerSport.
IIRC the wiring is not as straightforward as you would expect and involves the tacho plug which I presume supplies a stabilised voltage for the sender unit in the tank, which I believe is essentially resistive. I would check the tacho plug is connected properly and that all other instruments are reading correctly. On some cars, the engine harness plug is also used for some reason (but that could be a red herring).
Does the gauge do a sweep of the needle when you turn the ignition on ?
Occasionally mine doesn't and it then gives erroneous readings , turn the ignition off , watch the "sweep " and all is good again .
I dont know why it does that but without the correct " boot up " it doesnt read accurately .
Occasionally mine doesn't and it then gives erroneous readings , turn the ignition off , watch the "sweep " and all is good again .
I dont know why it does that but without the correct " boot up " it doesnt read accurately .
Interesting...
I tested the gauge earlier and it's OK (power and earth attached and shorted sender terminal to earth and it gave a full-scale deflection)
So am confident that the issue is with the sender side of things.
But I wonder if that test might have rebooted the gauge as you describe...
That said, there's no resistance on the feed from the fuel tank sender, so I think the issue's more likely to be there.
I tested the gauge earlier and it's OK (power and earth attached and shorted sender terminal to earth and it gave a full-scale deflection)
So am confident that the issue is with the sender side of things.
But I wonder if that test might have rebooted the gauge as you describe...
That said, there's no resistance on the feed from the fuel tank sender, so I think the issue's more likely to be there.
Gauge hasn't been rebooted... think mine are the older style, non-sweep-at-start-up style, anyway...
As DCL's commented... looking at the wiring diagram below, wire Y198 does seem to go between the fuel gauge and tacho... How is that connected to the float/sender in the tank?
As DCL's commented... looking at the wiring diagram below, wire Y198 does seem to go between the fuel gauge and tacho... How is that connected to the float/sender in the tank?
Edited by BigCol on Wednesday 26th April 18:48
Following more posts on 7-DNA (thanks DCL!) and BlatChat my conclusion was that the part of the tacho that parses the fuel level sender signal to the gauge was FUBAR.
My thanks to the chaps (Ian, James and Dave
) at PT Sports Cars in Windsor, who took a known good unit out of one of their cars and dropped it into mine; the gauge then showed a reading.
Good news - my diagnosis was right! Bad news, I have trashed part of £180-worth of tacho!
Caterham have stock, so I should have a replacement this time tomorrow ahead of me driving to Blyton!
My thanks to the chaps (Ian, James and Dave
) at PT Sports Cars in Windsor, who took a known good unit out of one of their cars and dropped it into mine; the gauge then showed a reading.Good news - my diagnosis was right! Bad news, I have trashed part of £180-worth of tacho!
Caterham have stock, so I should have a replacement this time tomorrow ahead of me driving to Blyton!
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