2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

2nd gen gauge cluster ?

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Old Apr 12, 2002 | 02:59 PM
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2nd gen gauge cluster ?

Does anyone know if the gauge cluster only recives signals, or if it also sends them. I was thinking of making my own gauge cluster and was wondering if Id run into some problems....
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Old Apr 12, 2002 | 03:38 PM
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From: Rohnert Park CA
speed sensor is in the cluster it sends the signal to the power steering, cruise, AAS control unit.

The 20000 mile switch also sends a signal to the ECU

The cluster also jumps an ECU signal for the Alt warning, charge, and again the AAS.

and on a T2 the boost gauge is entirely controlled (both in and out signals) by the ECU.
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Old Apr 12, 2002 | 04:29 PM
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so could I build my own cluster, infront of the other one, leaving minimal parts/electronics behind my new one?
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Old Apr 12, 2002 | 04:57 PM
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Yeah, I am not sure what the 20000 miles switch does (it is a second odometer piggy backed onto the first in the cluster) but other than that and having to plumb in your own boost gauge I wouldn't see any problems.

If you kept the stock speedo it would solve all the speed sense and 20000 mile switch problems.
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Old Apr 12, 2002 | 05:04 PM
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From: n
Originally posted by Icemark
and on a T2 the boost gauge is entirely controlled (both in and out signals) by the ECU.
This was what I used to believe too, but after doing some minor troubleshooting for someone on their high RPM hesitation problem, the Mazda factory manual schematics clearly shows that the instrument cluster boost gauge is actually spliced into the boost gauge signal before it hits the ECU, making it run totally independent from the ECU itself.



-Ted
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Old Apr 13, 2002 | 03:20 AM
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Im looking to eliminate the whole gauge cluster eventually...I want Omori gauges but they cant get their heads out of their asses! Ugh I need to make some decisions soon...
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Old Apr 16, 2002 | 12:19 PM
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Originally posted by RETed

This was what I used to believe too, but after doing some minor troubleshooting for someone on their high RPM hesitation problem, the Mazda factory manual schematics clearly shows that the instrument cluster boost gauge is actually spliced into the boost gauge signal before it hits the ECU, making it run totally independent from the ECU itself.



-Ted
Hi Ted...

Looking at the ECU diagram, I would agree with you. Looking at the gauge cluster diagram, it appears to be controlled by the ECU.

I'm currently troubleshooting a problem here: https://www.rx7club.com/forum/showth...ht=boost+gauge

When my pressure sensor is disconnected, my stock gauge goes up to almost +40. It is receiving the voltage that should result at 5lbs of boost (default when sensor is disconnected). This tells me that the ECU is sending that signal to the gauge.

If it was t'ed in to the line as it shows on the ECU wiring diagram, I would think it would be dead when the pressure sensor is unhooked.

Again... I'm still troubleshooting, so this is just what I have found so far.

-Matt
'93 Touring
'87 Turbo II
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Old Apr 16, 2002 | 12:37 PM
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From: n
Originally posted by matt_ledbetter
When my pressure sensor is disconnected, my stock gauge goes up to almost +40. It is receiving the voltage that should result at 5lbs of boost (default when sensor is disconnected). This tells me that the ECU is sending that signal to the gauge.

If it was t'ed in to the line as it shows on the ECU wiring diagram, I would think it would be dead when the pressure sensor is unhooked.
Uh, wouldn't the boost gauge not respond if it's unplugged?&nbsp Is this your experience or the general experience with everyone else's FC?



-Ted
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Old Apr 16, 2002 | 12:49 PM
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Originally posted by RETed

Uh, wouldn't the boost gauge not respond if it's unplugged?&nbsp Is this your experience or the general experience with everyone else's FC?



-Ted
This is my experience on my '87 Turbo II. The pressure sensor is unplugged and the boost gauge shoots up to one or 2 ticks under max on the stock gauge and stays there. I believe the ECU is sending the default voltage for a pressure sensor failure which is equal to 5lbs of boost.

-Matt
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