tach and speedo went out
 

hey guys,
I have a friend and his both the spedo and tach just stop working? anyone know what it might be? i think its the computer but i have read that the ECU doesn't send a signal to the Dash, the trailing coil pack does. it could be the Cold solder joints or corroded screws on the back of the cluster. What do you guys think?

any suggestions would be very helpful

thanks

so no one has any ideas?

isnt the Speedometer is mechanical? If it is we can go
from there. But even if, I dont know why the tach would drop dead too..

The speedometer is electrical. Sending unit is on trans.

Cool, I never messed with it all, good info...Thanks CANT

Thanks for the info can't

my odometer went the other day. I just got in the car and those little comforting lights with 90k on them just went. any ideas of how i can fix this without going and spending like $1000 .

tach and speedometer
 

when my speedometer went out, it was because of
my old O2 sensor. bought a new one and it started working again. when my tachometer was out. i knew
it couldve been the coils or the tack itself. i went out
and bought a new tach from a mazda dealer. 600 dollars. replaced the tach with the new one and it worked again.


speedometer - check the O2 sensor


tach - check the coils or the tach itself

my friend just plugged the double throttle lines open and then they both died, if that helps.

Ok, I just wanted to bring back this thread to say i finnaly got around to fixing my friends dash/gauge cluster (since almost nobody follows up on their stories). In anycase, it turns out it was a cold solder point for a transistor on the back of the speedometer.
You could clearly see that the solder broke off. I alsot found out that tach runs directly off the speedometer.

The reason why it took me about 6 months to fix is cuz he just never got the time to come over to my house and let me tinker with it. (Actual fix time was pretty damn fast). At least tomorrow, there will be one more FD on the road which is fixed :D

On another note, since I got the dash guages cluster off and just sitting on my desk, I'll be working on a CF overlay for it :D Look for pics soon

cool, good job.

wow!! someone followed up! good job!! :D

hmm well can you help me with my problem... If I accell hard in 1st or 2nd gear to where the nose of the car jumps up a little my tach and speedo will drop to 0 until I key off then on again. The odometer goes as well. My PFC still reads tach but no speed and I have a blitz turbo timer which reads speed. I was thinking maybe a bad connection where the blitz is hooked to the speed sensor, but would that cause the tach and odo to go as well?

yeah, its probally the speedometer (cold solder joints). If you have ever taken your instrument pannel out (which by the way is super easy, just 2 screws are holding it in and you just yank the sucker out, you dont even need to take off the steering wheel!) All the info for the tach comes from the speedometer. I suggest taking it apart and going over every solder connection in a grid pattern to look for missing solder joints.

here are some pics I took, the pen is pointing to where the solder was missing.
http://silverfd.efiunlimited.com/dash/

Good luck.

P.S. Is your blitz turbo timer constantly working to read speed or does it go out. As I understand it, when you take off really hard, both your stock tach and speedometer stop working, your pfc speedometer stops working and the blitz turbo timer reads rpm just fine and never turns off. Is this correct?

Thanks for the info I forgot to check up on it, cuz it stopped when I put my new suspention in. Now The tach has a mind of its own and sometimes will hang at 9k or 4k. It usually works when I first start the car but only for a second then it hangs at 1.5k and creeps up as I drive. By the time I have the car back in the garage its at 9 and will stay there for a while even when the car is off.

So the solder is actually on the breadboard? damn thats hardcore, guess better than spending 600$ on a tach though.

The blitz turbo timer read speed out fine after the speedo cut out. But yeah the Power FC read out. Now with the tach problem my Power FC will still readout... so probably something with the gauge huh.

Thanks,
Chris