Radiator Fans, ECU Fuse Blows

[Sailor96]

Problem for you gents,

Driving around running really well, not in a limp mode condition, but the fans weren't switching on and temps were rising dangerously above normal

I tried using nistune to diagnose the problem and couldn't connect through the consult cable initially. Found the 10A fuze was blown for the ECU (bottom right 4th up).

Managed to connect to the ECU with a higher amperage for only a moment, didn't see any temp sensor faults.

Disconnected the fans and put in another 10A fuse and it still blew.

New OEM Nissan fan relay I just installed last weekend and the fuse still popped.

Anyone had this issue before? TIA

 

[Luke1134]

Hello,
I haven't had this issue before but looking at it from a wiring point of view if this is the fuse that is blowing for you then you have a short to ground on this wire or potentially within the S.M.J or up to the relay, as this fuse is getting its supply from the ignition switch and is grounded from through the relay coil, if that fuse is blowing then it should be a short to ground on that live wire. I wouldn't recommend using higher amperage fuses as this runs the risk of fire with a short, if you don't want to go tracing through the loom/wiring to find where its shorting the easiest thing would be to cut that wire and run a new one, which will save you alot of time but if this is shorting with other wires then you could have further issues and will have to find and trace as to where its shorting. There is a potential for the fuse box itself to be shorted on that fuse also but a quick continuity check with the fuse removed should confirm the fuse box ok.

 

[Sailor96]

if this is the fuse that is blowing for you then you have a short to ground on this wire or potentially within the S.M.J or up to the relay, as this fuse is getting its supply from the ignition switch and is grounded from through the relay coil, if that fuse is blowing then it should be a short to ground on that live wire.

I verified continuity at the fuse box and there was no continuity, so the fuse box is okay.

I ran another test from the outlet of the 10A to the fan relay, which had continuity through the wire.

Then from the same relay to body ground and it also had continuity, which if I'm not mistaken is a unwanted short?

I'm trying to find the connector at the moment to see which side of the connector the short is on to narrow it down a bit

On a side note. The manuals circuit diagram labels the relay as the "fuel pump relay", but the "rad fan1" relay has the correct corresponding wire colors and has been the one I've taken all the tests from. But overall has been a confusing conflict of information

 

[Sailor96]

More confused now then ever

Disassembled the SMJ separating the two connectors. The engine side has the male connector pins, the interior side female.

Tested between the 10A and SMJ C4 (female), all good and not grounded.

Tested between SMJ C4 (male) to Rad Fan1 relay, again all good and not ground

I can't help but think it might actually be the fuel pump relay... But the wire matches the diagram with W/G(white green stripe) and L(blue) on the coil side of the relay. The SMJ C4 location seemed off, but the same white green wire came off the male side that I tested