Coolant gauge issue

Jhill

You're pretty safe to check it as the ECM typically have their own resistor in series before the output and that is how they determine a dead short or open as the sensors operating is typically .7-4.5 so if it sees 0 or 5 it know there is an open or short. On sensors that have a sig return it's a little different and if you screw the ref up well like the saying goes garbage in garbage out. Before you even venture in this journey I would highly recommend you pull those codes and get the wiring diagrams that go with those systems. Without proper documentation you are just guessing.

SouthArk370Z

There you go, Wilson. You have two "electrical guys", one with general experience and one that specialized in automotive (it would be foolish not to listen to him), telling you the same thing. We can't be certain the wiring is the problem, but, it's the first place we would check.

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Wilson2608

I'll post back with my results !

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Stillen G3, z1 Intake Manifold, Stillen Headers, Z1 HFC's, Stillen Catback. 330whp 267 ft- lbs tuned at Z1 motorsports.

SouthArk370Z

You will probably like this, too: Ecm/bcm wiring diagram with pics (tech sheet)

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Jhill

So any updates yet? Curious as to what you find.

Wilson2608

I'm on vacation at the moment but it's keeping me up at night thinking about it hahaha. I will update sometime this weekend when I return.

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Stillen G3, z1 Intake Manifold, Stillen Headers, Z1 HFC's, Stillen Catback. 330whp 267 ft- lbs tuned at Z1 motorsports.

Wilson2608

Alright so here's a long overdue update. I got back and my issue returned with both my coolant and fuel gauge reading low at all times. I took out the fuel pump and checked for shorts in the wires and there were none. I used my multimeter and unplugged the resistors to get a voltage reading to the sensors. (Fuel level sensor and fuel temp). I got a full 12v to the fuel sending unit and a 5v to the fuel temp sensor. So both seem to be getting their full amount of power. I did a resistance test on both gauges and the fuel level sensor failed. It's weird because I tested it right before I installed it the first time and it checked out okay. Funny how things break like that, I may of been to rough installing it idk. Anyways when I tested the resistance on the fuel temp I got 1.5, 1.6ohms. I need to dig in the service manual to check its specifications.

As for the coolant sensor I haven't really looked at it too much, I'm not throwing a code for it but I know it's not reading right. With my diagnostics tool plugged in it reads 130 degrees, but with my hand held thermometer it reads 180ish. So I know somethings up. When I turn the car off and just turn on the electricity it reads fine.

I'll update you when I find out more. HAPPY FOURTH OF JULY!!

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Stillen G3, z1 Intake Manifold, Stillen Headers, Z1 HFC's, Stillen Catback. 330whp 267 ft- lbs tuned at Z1 motorsports.

Jhill

Fuel temp sensor? I'm not sure what your referring to but I don't believe these have a fuel temp sensor, again not a Nissan tech but that would be pretty odd to have. Are you sure your not looking at a fuel tank pressure sensor? Also if your checking to see if something is pulling down the 5v ref then you need to do so plugged in otherwise if something was pulling it down and you disconnect to check 5v at the terminal you have just fixed your issue without even realizing it only to have the same issue once plugged back in. Looks like I am going to have to go through that manual when I get home and get a better idea what you are looking at.

Just did some googling and you are correct it does have a fuel temp sensor. That's actually kind of neat, never really paid much attention to that before.

Wilson2608

Yes I checked it while plugged in, I actually took the whole assembley out and tested it from there. I think I know what the issue is though, after switching the RIGHT resistance setting on my multimeter (noob mistake) i realized that my fuel level sensor is not broken. Once i pulled it all out i played with the sensor and raised it to the full position as i observed the gas gauge, it worked fine and the gas gauge read 3/4 a tank. (had a half tank of gas and we have 2 sensors so the avg was 3/4 a tank) I think what has caused my problems is my jerry rig. I believe its too short and the temp sesnor and fuel level sensor isnt even touching any gas in the tank when below like half a tank. I ordered a new one from courtesy Nissan parts for 350$ (opposed to the local dealships 450) so i guess i cant complain. I really wanted the billet topped one CJM is making but I can't wait any longer I need a legit non jerry rigged product in my car. I will keep you updated, the new part will be going in Thursday.

Again thanks to both of you for the input!

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Stillen G3, z1 Intake Manifold, Stillen Headers, Z1 HFC's, Stillen Catback. 330whp 267 ft- lbs tuned at Z1 motorsports.