Tguigli

Too begin, Hello.

I look forward to learning more about theses fantastic cars. I have owned many cars and am fairly skilled with working on cars. However I have recently purchased my first z. To be specific, its a 2005 350z touring; and I have encountered a problem.

While purchasing the car I had the dealership fix two minor things. I wanted new trunk support struts, and the flashing airbag light diagnosed and repaired. Neither were completed as expected.

Anyway! the issue lies within the airbag light. They sent the car to a mechanic to have the light diagnosed and repaired. The car came back without an airbag light on. They said is was a "retaining spring". Anyway, I decided to check and see if the airbag light turns on when the key is turned to the "on" position. It doesn't. I feel they just pulled the bulb. However, at this point. Im fed up, its late, and I have had enough with the dealer. I ask for the mechanics information and I took the car and left.

But here is the problem. The fuel gauge is not correct, the speedometer is not correct and does not match the digital read out. and finally, the tachometer is not correct. It revs as normal until about 2500rpm where it sticks. (it sticks at different rpm sometimes). The gauges worked before.

I understand I can go back, I understand I can call the mechanic. This isn't a situational discussion. This is a question about a repair.

Anyway. Has anybody else experienced this? is there a way to "reset" or repair the gauge cluster. Why would the speedometer not match the digital one? What is going on with my gauge cluster.

Any help is greatly appreciated. Once again, I look forward to learning everything I can about these beautiful cars.

Thank you!

travlee

iTrader: (8)

was it a nissan dealership?

Tguigli

^^Yes it was. However, I have already made an appointment with the 3rd party mechanic Nissan used in order to have it repaired. (they had to use a 3rd party because they sent the car in on a saturday.)

Im just curious as to why the gauge cluster would behave this way. I mean, from what I have read, the entire cluster is electronic, but it can't be tuned, adjusted, or corrected. Which leaves be wondering.. How will this mechanic fix this problem? This just go against all of my experience with other cars.

KJFire4Life

iTrader: (6)

The mechanic diagnosis would involve testing the speedo/tach with a power probe or possibly finding a set of reference numbers for voltage across the gauges board. Along with physically checking the gauge board and faces for anything out of the norm. This almost sounds like a possible ECU issue to. But in accordance with it all starting with the airbag light being "turned off" (which sounds really fishy if it doesn't pass the check light test) I'd wager that the mechanic pulled the bulb out or it subsequently burned out (i doubt it) Have you had the airbag system checked for codes now? I would be very cautious of going back to the same mechanic. I say this as I do work in a shop and am blessed to have a boss that is honest to a fault, even if it costs him money, when it comes to customer relations and telling them whats up with their cars. One thing I do know is that Nissan electrical gremlins are HORRIBLE to deal with lol. If the mechanic can verify it's not an ECU they will probably try to put a new gauge cluster in. Since these are all electronic then there isn't a lot you can do to fix a single problem without tracing it through several other systems

Tguigli

I have not had the system checked since. Its only been a couple days. The situation with the mechanic through the nissan dealership sounds fishy to me too. Nothing quite sounds right. However, I am scheduled to take it back and I decided to because the shop feels confident they didn't finish the repair properly because they felt rushed from the dealer.. Regardless.. everything sounds fishy (even their "repair"). I going to see if they can fix it, they say they have a 200% guarantee.. so free of charge of course.. If they can't, Ill probably replace the cluster. I would have rather purchased the car with a flashing airbag light and working gauges..If they couldn't have fixed it right I would have rather heard "We can't fix it", that way I can diagnose it myself.. properly.

Also, I would find it hard to believe there could be an issue with the ECU. In my experience, if something goes wrong there, it effects everything; but everything else works great.. even the gauges in the center. Anyway. I appreciate your input and advice, it definitely gives me a little information to read into. Thank you

There is a reason I always work on my own car... and its this situation haha.

KJFire4Life

iTrader: (6)

Could not have said that better myself. If the shop is going to fix it the way they should've the first time. Free of charge of course, then take it back and see what they find out. ECU is far fetched but honestly not that far out, I've had many instances where small things are effected like a single switch or sensor and we traced it back to being a single burnt section of the ECU. Not saying that's the problem but it's worth just looking over for any physical problems. Anyway, keep us updated! Love to know how this turns out!

Tguigli

I definitely will keep you up to date. If they fix it, Im going to find out exactly what they did. Or, what they said they did. lol. If they can't, I will personally start diagnosing the problem. Anyway. Thanks again for the input. Im curious to see what happens.

karlt

If you look in the di.pdf section of the Service Manual you can get a good idea of how the instrument cluster (Nissan calls in the combination meter) works.

First of all, there are only 3 incandescent bulbs in the cluster - the 2 turn signal repeaters and the high beam indicator. The rest of the warning and indicator lights, and the backlighting, are LEDs. The incandescent bulbs can be replaced relatively easily once the cluster is removed from the car, but removing or disconnecting an LED requires disassembling the instrument cluster itself, a task not covered in the Service Manual.

Signals for the gauges and lights come to the instrument cluster via a 24-pin connector. Many come from the Unified Meter and A/C Amp, located behind the heater and air conditioner *****. Water temperature, fuel quantity and rpm come over a dedicated 2-wire digital link (not the regular vehicle CAN bus), and road speed is via an 8-pulse signal on a different contact. With fuel quantity and rpm in error, I would ask if your coolant temperature gauge is also in error.

As for the air bag light, it could be disabled by applying a ground to pin 2 of the 24-pin connector. If the tech who worked on the car tried to do something like that, he may have damaged or misaligned some of the pins on the connector, which could explain your problems.

Tguigli

^^ that was an awesome load of information, and I will look up the wiring diagram for the instrument cluster soon and test what I can with a multimeter. I already knew about the bulb layout mostly. However, when the shop finishes everything and either fixes, or does not fix the problem, I will definitely find a diagram and try to troubleshoot more accurately.

And as far as the temp gauge being incorrect.. I felt it was too, but it stays directly at 9 O'clock (sideways gauge as we all know) during normal operation temp, and it doesn't move, I feel that somehow its correct. Also, the gauges in the center console are accurate.. and using simple judgements, the odometer follows the digital speedometer. The oil pressure stays within normal range, and voltage is correct.. 12.5 (with key in "on" position) and just over 14 when the car is running. and finally, the digital speedometer is only 2mph off which is a small enough standard deviation that I consider it correct... in comparison, the analog speedometer reads 6-7 mph off, the tachometer gets stuck at specific rpm and jumps, the fuel light comes on at a quarter tank, and judging by fill ups, the analog gauge is incorrect too because it will read 75% full, when it really is only a half tank.. regardless, I will see if they can repair it. and if not, I'll begin some serious research.

I appreciate all responses, and this load of information. It has guided my thinking and will help the diagnosing process exponentially should the car return not repaired. (Ill be dropping it off Monday) . Thanks.

karlt

Thank you for the compliment. I'm not surprised that your triple meters are unaffected. They get their information either directly (oil pressure and voltage) or from the Unified Meter and A/C Amp. I don't believe they get anything from the instrument cluster. Good luck with your repairs.

jtbinvalrico

Those hacks screwed up your car trying to kill that SRS light. 1st: Get yourself a scan tool so you can stay ahead of these problems and not be jerked around by these guys. The Autel 619 will read SRS and other codes on that car and your others as well. 2nd: When you pull the code, I bet it's the typical driver side alert, which is often the clockspring (barring crash issues).

As for the rest of the gauge issues......When you show them the fault code for the SRS, they should realize they're busted and need to fix the gauges/wiring they monkeyed around with.

zakmartin

Let the shop or the dealership fix the problem. It was agreed to that they would when you purchased the vehicle. For you to try to go in and fix it yourself will basically mean you forfeit any expenses and time incurred on the repair and will have to take it on yourself, which is, let's face it, asinine.

Have them repair the vehicle and tell them you want to see any parts that required replacement and you want documentation of what was done. Take photos of the parts or take them home (if they allow or the law requires).

You're setting yourself up for a) disappointment, and b) no legal recourse if you decide to take the responsibility of the repair away from them and just shade tree it yourself.

FYI - If they intentionally disabled or modified your SRS system to make the light go off, as you believe, that is a prosecutable crime.

Tguigli

Alrighty! I have news. The mechanic the dealership used actually turned out to be legit. It isn't a large shop as he is more into electronics and programming rather than turning a wrench. This guy is the owner and personally works on his cars and is incredible with electronics and coding.

ANYWAY! The story is as follows. Originally, they took the car in from the dealer to fix the airbag light. They scanned the vehicle and found the issue to be a clockspring. They replaced that, and quickly reassembled the car and returned it because the dealer was pressuring them. I took it back on Monday and he was able to finish the job right. The tachometer and fuel gauge were incorrect because a connector in the BCM (Body Control Module) that was supposed to pass 5 volts had corrosion and occasionally had voltage drop down to about 2.5 volts. Therefore the cluster was not completely operational. He cleaned the ground and reprogrammed the cluster and everything worked beautifully.... except the speedometer.
He then removed the gauge cluster and hooked it into a separate computer and bench tested it and checked all of the available information. For some reason, after resetting the cluster, it defaulted to KPH and not MPH. He then reprogrammed it correctly, therefore correcting the speedometer. To conclude, all gauges are operational, and I am taking it back Monday for him to replace the ground that continues to become corroded... If anything in this post doesn't make sense, I apologize. It is a complex situation and according to my research, an accurate one. If anybody has any specific questions or wants clarification, I will gladly reply.

Anyway, this tech has had a lot of experience building engines and in general automotive technology. He is also very knowledgable about the 350z and its tolerances. He is also going to school for avionics (though unrelated to cars, still impressive lol). Overall, a very intelligent and reliable guy. EXCELLENT for anything electronic.

I learned a lot about the BCM in this situation, and if anybody ever has any strange electrical problems excluding engine management, I highly recommend testing individual circuits first and looking for anything unusual. Should somebody not find the issue, look at the BCM. It acts as a ground for most of the auxiliary circuits such as the radio, lights, gauges, etc.

Cheers.

zakmartin

Great follow-up. Thanks for letting us know how this turned out.