Coolant gauge issue

SouthArk370Z

I am glad to hear that you are learning how to work on cars. It will save you a lot of money in the future and may get you out of a bind when the car goes into limp mode some moonless night on a deserted road. And it can be very satisfying. But sometimes you have to get some help or farm the job out to someone else. I was an electrician and instrument tech for a couple of decades and I would still suspect the wiring if I had done the job - feces occurs. Find somebody that knows a little bit about electricity/electronics and get them to help you trouble-shoot. Figuring out what is wrong should be pretty easy (fixing it may not turn out that way, but that's another thread).

I am not 100% certain that the problem is not somewhere else but am pretty sure the problem is related to what you did. If not the external wiring, then the internal wiring of the sensors. The timing is right and the symptoms seem to point in that direction. Maybe you shorted something out in the ECM or there is a wiring problem in the engine compartment.

And NEVER work on fuel systems, brakes, traction control, &c unless you know what you are doing. If you have any doubts, find someone that knows what they are doing to help.

PS: Disconnect the battery before doing any electrical work. You can find the procedure in FSM or many threads on this site. The same threads will usually tell you how to reset windows and other quirks that pop up when the power is killed.

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Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

Wilson2608

Hahaha hopefully that doesn't happen 😂. I'll double check the wiring for shorts and if I can't figure it out I'll at least pay Nissan the 100$ to diagnose the issue.

Thanks south ark! As I said before I really do appreciate 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.

Jhill

as a journeyman level drivability/electrical diag tech for the last 11 years, up until this last year when finally leaving automotive to actually make a living so I can afford my own z and not fix everyone else, or in my case everyone else's corvette. Loved the work (once I got to a specialized role, no heavy duty, didn't have to do anymore engine R&R or trans etc,) hated the pay and the BS warranty times etc etc.. but I am fairly certain (I'm not there testing so I cant say 100% without a doubt) that you goofed on your wiring. Maybe you screwed up and wired something into the fuel tank pressure sensor? the multiple high voltage codes you have would re enforce my believe that somehow you have screwed up the 5v ref. and the timing of it too.

Wilson2608

Okay I'll be reading through the FSM today to gather as much info as I can and see if the two circuits have any common route. Both my codes are high input codes. I honestly think I know what is causing those codes though. When I depressurized the fuel lines I didn't unplug the fuse. I just unplugged the fuel pump and cranked the car. Yeah obviously that will throw a Cel and I knew that from the beggining, I just figured it doesn't matter and it'll be fine once I clear the codes. I bet that has something to do with the short or wiring issue. So basically, to test for the 5v reference I can use my multimeter at certain sensors and test for the 5v power supply?

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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

On my way to work this morning both the fuel gauge and coolant temp gauge started working fine. So weird..

Im sure the gas gauge is still off due to what I had to do in order to get the fuel pump housing top and bottom to hook up right, but at least its reading.

Only issue now is I still have the CEL and the car tends to idle a little high. (1100 rpm) I think thats due to the fuel temp sesnor code.

Like I said before ill check the fuel temp sesnor wiring for shorts and post back!

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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

Please get some help before you kill some electrical component(s) or start a fire.

But, yes, a decent multimeter and tools to access the wiring/sensors should be all you need. I'm guessing that the problem will be pretty obvious with a visual inspection.

I haven't looked at the wiring diagrams but the 5V reference that Jhill refers to may be internal to the ECM. If so, you will need to check it at the ECM (if possible). If the outputs from the sensors are out of spec (I'm betting that will be the case), the reference is probably not the problem. The 5V ref is just a possibility. I think (and it seems that JHill agrees) that the wiring/sensors is the most likely culprit.

__________________
Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub
Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

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

IF the person using the meter knows what they are doing. Even if the ECM is bullet-proof, I'd hate to muck around, short some wires, and put 12V where it doesn't belong (like inside the gas tank). If it were you doing it, I wouldn't be too concerned - I'm not sure OP has acquired the skills to do the job safely.

__________________
Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub
Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

Jhill

Too true. I've seen so called master techs do **** that I still shake my head at. It can be scary out there.

Wilson2608

Both of you are obviously very knowledable about cars/ electrical work, and i basically know little to none about this kind of stuff. But im adament about doing the work myself for the purpose of becoming more educated. When my engine blew in my 300zx I took it upon myself to do a motor swap. It took me like 2-3 months, but eventually i got it perfect with no issues at all. And now i could do it in half that time, and thats the reason I want to fix this issue too. I will follow the procesdure in the FSM so I don't mess anything up and i'll let you guys know!

Thanks so much for help mates

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