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I too wish to rewire this circuit, I am now having the same issue as numerous people have brought up about the Sub tank light remaining on all of the time. I have done the "remove power from battery" numerous times in my trip from Wodonga to Darwin to try and utilise both tanks but it's getting a bit ridicules doing this on almost a daily basis. Has anyone actually solved this problem yet, reading all of the other threads on this topic has not given any info other then cleaning terminals, disconnecting the battery or fitting an additional earth strap. What is the purpose of the sub tank controller behind the radio, if the tank has to be manually transferred anyway, why would it need a controller apart from pumping some fuel between tanks on start up, can this be removed from the circuit to provide a direct link to the transfer pump whilst using the existing switch.
Has anyone actually done this modification or even come close to solving this issue.
Have you installed an earth strap to the chassis?
You can wire a simple on/off switch to run the fuel transfer pump if you like.
The controller is to make sure you don't overfill the main tank and that fuel transfer stops when the sub tank is empty so you don't run the fuel pump dry.
Do you still have standard fuel tanks or long range tanks fitted?
I haven't actually put an earth strap on, was more interested in actually discovering what caused the problems rather then just putting a 'fix' on. In saying that I have not had the light come on for three days since I stopped letting the turbo timer switch the car off. Running a simple on/off switch, that's what the switch on the dash is anyway, so to run another without solving the issue seems pointless unless I remove the controller.
I haven't actually put an earth strap on, was more interested in actually discovering what caused the problems rather then just putting a 'fix' on. In saying that I have not had the light come on for three days since I stopped letting the turbo timer switch the car off. Running a simple on/off switch, that's what the switch on the dash is anyway, so to run another without solving the issue seems pointless unless I remove the controller.
The chassis is not earthed from factory. Nissan wiring (including earth circuits) is only just satisfactory for a standard vehicle. Once you start modifying it, adding extra electrical accessories and the wiring starts getting old this can cause all sorts of electrical problems. One "fix" is to add an earth strap between the body and chassis. This has even been recommended by Nissan. For something that cost so little to do I find it strange that you don't want to do it.
Another known cause of fuel transfer electrical problems is the shut down timer. If the incorrect one has been installed this will bring on the sub tank light.
The original fuel transfer switch is not an on/off switch it is a momentary switch. When the switch is pressed it sends a signal to the sub tank control unit. Then if the control unit sees all the correct information from the sensors in both fuel tanks it will switch on the fuel pump. I think the control unit also measures the power the fuel transfer pump is using and if this is out of spec or any of the other sensors are out of spec the control unit stops the fuel transfer and brings on the light.
In your other post you said "I too wish to rewire this circuit". The easiest way to do this is to fit an on/off switch in the dash to switch a relay on and off that turns the fuel pump on and off. Then just remember to switch the pump off because the biggest killer of pumps is to run them dry.
The chassis is not earthed from factory. Nissan wiring (including earth circuits) is only just satisfactory for a standard vehicle. Once you start modifying it, adding extra electrical accessories and the wiring starts getting old this can cause all sorts of electrical problems. One "fix" is to add an earth strap between the body and chassis. This has even been recommended by Nissan. For something that cost so little to do I find it strange that you don't want to do .
Hey rod is this just an extension of the body earth to the chassis , I'm not having any issues but it is s simple thing and I prefer prevention over a future falt . Sorry for the high jack
Steve
Last edited by gaddy; 12th January 2014 at 11:33 PM.
Hey rod is this just an extension of the body earth to the chassis , I'm not having any issues but it is s simple thing and I prefer prevention over a future falt . Sorry for the high jack
Steve
That will work fine.
Most people connect the earth from the body to the chassis near the fuel tanks.
Originally Posted by Ian2011
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