Installed a stereo, Tach and Econo gauge stop working.

[SkorcherX]

Hey Guys,

I had my interior out of my car for about 5+ months. I also had the battery disconnected from the car. I finally got a new stereo put in (all new wires, speakers, amps, sub... everything). Stereo works great.

I put the rest of the interior and dash together, plugged the instrument cluster back in... no tach or econo gauge.

I find that the SI batteries are prolly dead. I buy new ones and install them. Still no tach and econo gauge.

I swap cluster with older 325e cluster... still nothing.

Keep in mind that every other light and gauge in the car work great. Windows work, locks work, lights, everything.

My tach and econo gauge used to work. The only wires touched during this project were ones related to the stereo. What are some things I can do to troubleshoot this?

Thanks!

[der affe]

I had something similar happen, but lost all the dome and trunk lights too (I have MSII so the econo gauge does not work) check the related fuses with a test light and replace as needed. Also make sure the flashlight plug in does not have something stuck in it causing a short.

[SkorcherX]

I put the volt meter to every fuse I had, making sure I got a "beep" out of each one.

[beta14ok]

I've had this happen. Pull the cluster and reseat all of the connectors (especially the big one on the right hand side behind the tach). I that doesn't work, clean the connectors and reseat again.

[SkorcherX]

I've had this happen. Pull the cluster and reseat all of the connectors (especially the big one on the right hand side behind the tach). I that doesn't work, clean the connectors and reseat again.

I have had the cluster in and out at least 10+ times over the coarse of troubleshooting this. I do not believe that it is a connection problem at any of the plugs.

I am leaning towards some wire that provides power (?) to the cluster perhaps no longer is. And is now powering the stereo instead? That is my hypothesis.

Everything in the gauge cluster works. All the lights come on, all the dummy lights light, the SI lights are solid, everything works. However the tach and the econo gauge... are lifeless.

Any additional troubleshooting steps would be greatly appreciated.

[ACS Cabrio]

I have had the cluster in and out at least 10+ times over the coarse of troubleshooting this. I do not believe that it is a connection problem at any of the plugs.

I am leaning towards some wire that provides power (?) to the cluster perhaps no longer is. And is now powering the stereo instead? That is my hypothesis.

Everything in the gauge cluster works. All the lights come on, all the dummy lights light, the SI lights are solid, everything works. However the tach and the econo gauge... are lifeless.

Any additional troubleshooting steps would be greatly appreciated.

have access to a known working cluster to test with? At least that way you can rule out your cluster being broken

[SkorcherX]

have access to a known working cluster to test with? At least that way you can rule out your cluster being broken

I need to do this. I do not have a known good 325i cluster at my disposal. I posted on the regional forum thread but have not gotten any one to lend a hand.

[Gregs///M]

Most likely your Si board batteries died while the battery was disconnected. This is very common on our cars. You'll need to buy new batteries and solder them into the SI board or buy a refurbished one. See my thread in signature for more info.

SI board directly powers and feeds signal to the tach, temp and eco gauge.

[SkorcherX]

Most likely your Si board batteries died while the battery was disconnected. This is very common on our cars. You'll need to buy new batteries and solder them into the SI board or buy a refurbished one. See my thread in signature for more info.

SI board directly powers and feeds signal to the tach, temp and eco gauge.

Hey Gregs, thanks for the help, but I explained that I already went this route without success in my initial post.

[achtunge30]

In my previous experience, you may be missing a connection with your new radio. I know this only because I once drove the car without the headunit harness plugged in and I too was missing tach and econo-gauge.

[Acehye]

Where are you getting the headunit ground and power from? Make sure it's not from the obc wires.

[Gregs///M]

I know for a fact that your tach and eco gauge will NOT fail to operate if your head unit is unplugged as Achtunge30 said.

However, it is very real possibly that the head unit wires were tapped into the wrong wires leading to the cluster since they route through the back of the head unit cavity.

Engine speed comes from the ECM to the cluster into the blue connector, black wire. This wire will show pulsating signal while the engine is running. You can test with a probe or meter. Set the meter to AC volts (1.5-6V AC). AC volts should increase as engine RPM increase.

If you find your wiring (at the cluster blue connector) has this pulsating signal, the problem lies in the cluster.