erratic tach reading
 

Hey guys I'm in need of help, the tachometer on my 2012 nismo has been erratic. Even when the car is at idle the needle will sit at something crazy high, even well past the redline at times. Everything runs fine, just the tach is all jacked up. I have no idea where to look for the wires or anything that might possibly be the problem.. any info would be greatly appreciated. :icon14:

Like while you're driving? And the car sounds and drives ok? If so, there's most likely a bad connection somewhere with the dash harness. Most likely a damaged or loose connector or the tach lead could even have come loose from the harness. Could be the tach itself, but that appears to be far less likely.

yes everything runs just fine, the engine sounds completely normal. I can be cruising around in 6th gear, when the needle should be around 2-3k, its sitting way above that and sometimes completely past all of the numbers lol. It isn't intermittent either, it is constantly reading something inaccurate.

What JARblue said. If the problem was with the sensor/ECM, the car wouldn't run right.

so this may be a dumb question, but do I need to begin by pulling the cluster out and looking behind there?

Are you going to be doing this yourself, and if so, are you comfortable doing this kind of work? Personally, I would take it to a competent shop. But if you insist on doing the work yourself, you're going to want to reference the FSM before you get started. It will tell you where the dash harness and tach lead is located for troubleshooting. I would assume the answer to your question is yes, but that job is such a pain I wouldn't start it without knowing for sure the wiring you need to check is back there.

I believe I can handle the task, the main thing for me is knowing where to begin looking and I wanted to see if anyone on here had dealt with something like this. Referencing the FSM is a good idea, I really appreciate the advice!

Not being a Nissan tech I can't say without a doubt but I would be really surprised if it were not the cluster itself. The reason I say this is today's cars all use networking with multiple modules and your cluster will be one of those modules. So your looking at power, ground, can hi, can lo, possibly tied in with body can system as well and that is about for wiring. If all your other readings are correct then the cluster itself has in internal issue that you won't be able to service. Will have to go to dealer for new cluster, programming of mi etc.

If you have access to an OBDII Bluetooth reader and app on your phone (like Torque Pro), use it to see what is coming from the computer. If this reads OK and the needle is still not accurate, I would say that there is something physically wrong with the tach (electrical or mechanical)

I don't think the car would run right if ECM was getting a bad signal or computing a bogus value. But it's easy enough to check and OP is going to want a reader before this project is over (IIRC, all gauges, except clock in triple-gauge get their data over OBD/CAN) so why not?

Correct, therefore if all other cluster functions are operating correctly (lights, gauges, speedo, etc) then you can rule out a bad connection. It's not like your old car where your tach is connected to the ignition coil neg terminal or receiving a direct signal from a ignition control module. It is getting its data on the same comm lines as all the rest of the data, which would mean there is an internal issue with the tach and that is not serviceable (or at least none I have ever seen are).

Ah. Thanks for clearing that up for me.

Tachometer issues
 

Did you ever find out the problem with that ??? I have the same issue 😪