1993 RX-7, 19K miles. Manual transmission. Original and unmodified. I have all Mazda Service Manuals for vehicle.

Have reviewed Archives/Search and not found sufficient information to solve all problems.


Problems/Symptoms:

Odometer is blank and have reviewed the "fix" posted by "Turbo Blue". Thanks TB. All other gauges function. Backlight for odo. works. Speedo sensor checks o.k. via the Cruise Control diagnostics. Cluster in on kitchen table, disassembled and ready for un-soldering. Waiting for parts.

Cruise Control: When engaged, CC hunts/surges/accel's/decel's for 10 to 15 seconds and then kicks off. CC passes all diagnostic tests. Actuator motor passes all diagnostic tests.

Air Bag Diagnostic Module: Air bag warning light flashing the priority 7 "10" code indicating module has blown its internal fuse due to short/failure of one of 3 "D" sensors.

Questions:

If I understand the C-1a wiring diagram correctly, speedo sensor sends signal to speedometer/CPU and then signal is split to odo and cruise control. Could odo and c.c. problem be related? If signal is "bad" out of speedometer, might this possibly affect odo and ability of c.c. to hold speed?

If two are not possibly related. Since cruise control and actuator motor diagnostics check out o.k., where else should I look? I figure if the speed sensor checks o.k. and the actuator motor checks o.k., then the problem must be in the middle (speedometer signal). How's my logic sound?

HTF do you get to the speedo sensor on the gear box? No access to lift. Is the sensor on the right or left side of g.b.? Two out of 3 diagrams in manuals show right side another left for manual transmission. Manual(s) do not say how to get to switch, just steps to remove and test. Looking for a little clarity. Could not find a way through the trans tunnel on the interior...so I figure you must get at it from underneath. True?

Last, the air bag diagnostic module. The "10" blink code is intermittent. On for a while, then off for a while (days). Seems if I drive over 100 mph it resets, but I do not see this in writing anywhere. I am perplexed as this code says an internal fuse has been tripped in the module. If this is the case, why would it be intermittent?

Mazda says this module is no longer available. One dealer quoted $811 and another $2100...thank God they are not available! Has anyone had luck rebuilding these or fixing this particular problem?


Sorry for the shotgun approach to my first post here. Looks like a great site with a wealth of information. I hope I can contribute to the group in the near future with useful info. myself.

Thank you all,

Bill Glaser

 

The speedo sensor is on the passenger side of the trans. Not hard to remove, but you have to be able to get under the car somehow. You'll also have to reach the plug for the sensor which has about a 12" lead and I believe it connects further up on top of the tranny. Going in from the shifter opening will probably be no help btw.



I would not buy a new sensor from Mazda. They cost a couple hundred bucks or more and there are plenty of good used ones available for a fraction of that. In fact I have a couple of spares if you're interested.

I agree that I'd troubleshoot the speedo issue before worrying about the cc at all. First, I could live without the cruise and therefore it would be less critical, and second without a good speed signal the cruise will not be able to function properly.

Dave

 

Dave, thanks so much for the picture and description. Looks like you probably are showing the "best" way to get at that sensor! I do not think the sensor is bad, but will keep your offer in mind if I find myself traveling down that road.

First examination of speedometer board does not show anything obviously wrong with capacitors...but I am not an "electrical" kind of guy...my old man is an electrical engineer (retired NASA) and will assist his dumb son with the postmortem. Waiting on parts before proceeding with tear down. Hopefully someone will toss out some tidbits of advice on this subject in the interim (shameless begging).

And again, if anyone has intel. on the innards of the air bag diagnostic module or a rebuilder of these units...I know a guy who would be interested in hearing from you.



Bill G.

 

Hey Bill G.

I have the same issue and also have not had any luck with the air bag mudule. Did you ever get any answer to this question? I also would very much like to know. Thanks