DIY: instrument cluster diagnostics mode
 

This is kind of a repost, but the original thread was dedicated to something else and didn't go into much detail. Also, it didn't have the mazda specific codes and tests. Here's the deal:

Mazda and many other car companies have built a diagnostic mode into the instrument cluster in order to test out many important car functions and to determine whether all the car's sensors are working. Here's how you get into this diagnostic mode on the RX-8:

1. Insert key into ignition, but do not turn
2. Hold down trip reset button (on upper right of tach). This might clear your current trip meter, but i cant be sure because mine was already at zero.
3. While holding trip reset, turn key to the 'ON' position where the instrument cluster lights up
4. Continue to hold trip reset until the word "TEST" comes up in the odometer display.
5. Release trip reset.
6. Use the trip reset button to cycle through the series of diagnostic tests summarized below.
7. At any point, turn the car off and then back on to exit the diagnostic mode.

This is a pretty cool feature, though useless unless you suspect one of your sensors is broken. Here is what I could determine of the different modes:

Template:
[Mode]
[Display]
[Functionality]
- [Comments]

01
On/Off
Driver's Side Seatbelt Engaged/Disengaged (on if not clipped, off if buckled)

04
On/Off
Driver's Side Door Open/Closed (on if open, off if closed)

08
On/Off
Lights on/off (probably used for reminder buzzer)

12
Speedometer
Speedometer shows 'backwards 6' - 8 - 8
- On analog gauges, i think it's supposed to do full sweep
- Guess it doesn't work on digital

13
Tachometer
Performs a full tach sweep from 0 to max, then rests at 3k

14
on/off
Sounds instrument cluster buzzer

16
Fuel gauge and on/off
Flashes low fuel warning light

18
on/off
Flashes ignition key illumination red LED

22
numeric
Displays numeric value of fuel sensor's current level
- Kind of garbled display, but
- Very interesting to see how it works. Im going to test more.
- From my tests:
~320 = empty (very close anyway)
~220 = 1/2 tank
~10 = full tank

23
Fuel Gauge
Performs full sweep of fuel gauge from empty to full

25
Engine Temp Gauge
Performs full sweet of engine temperature gauge
- pauses at 1/2 on the way back down to zero

26
Whole Cluster
All light illuminated

28
Oil Pressure Gauge
Performs full sweep of oil pressure gauge
- but only goes to 1/2... maybe has to do with it maybe being a 'dummy gauge'?

50
displays "- -"
unknown functionality

51
displays "- -"
unknown functionality

55
on/off
unknown functionality


My personal favorite is the fuel gauge sensor display. I plan on seeing its reading at empty and full tanks.

If anyone figures out what 50, 51, and 55 do, please tell me.

Anyway, have fun! Hopefully this will help some of you troubleshoot any future senor/instrument cluster issues.

P.S. - I think i finally got the word "gauge" right on the first try. I swear it's impossible to remember which way to spell that word... or maybe i'm just an idiot.

Hmmm...interesting. I'm not sure I personally see much use in this for me right now, but it could come in handy in the future.

Gauge or Gage is fine. ;)

Thanks; always good to know these diagnostics.

those are kinda cool. thanks

no problem... if some of you wouldnt mind posting your actual fuel level and the numerical reading so i can compile a little reference guide, i would much appreciate it!

Uh, major re-post.

no i searched and searched, and the only other thing i could find was this:
https://www.rx8club.com/showthread.p...ter+diagnostic

that thread doesnt discuss anything mazda specific and was impossible to find unless you already knew what to search for.

Link to on-line manual
 

Maybe this will help:

link to FSM - Engine control & diagnostics

yeaaahhhh that thing was like 462 pages long and there was no table of contents or anything... i couldn't find it.

55 is the dimmer *all* the way up. like that click at the top.. i dont know what it is called, i'm a loser. and on 22, i noticed that the top number changed as i depressed the brake while the engine was off. From 125 to 109 or so.