Technical Service Bulletin
||Fluctuation in Cruise Control Set Speed
All 1999 Miatas with VINs lower than JM1NB35** X0 122015
During the auto cruise control function, any of the following problems may occur:
- Vehicle speed fluctuation
- Cruising speed is 5-7 m.p.h. higher than the set speed.
- Coast function (deceleration system) becomes inoperative.
These symptoms may be caused by a transistor malfunction inside the cruise control
unit. A modified part with a heavy duty transistor is available to resolve this concern.
Cutomers complaining of this concern should have their vehicle repaired using the
- Verify customer complaint.
- Measure the battery voltage and note it on the repair order.
- Turn the ignition switch ON, then turn the cruise control main switch ON.
- Measure voltage of cruise control module at terminal 'A' (G/Y wire). Refer to Section
01-20 of the Workshop Manual.
- If voltage at terminal 'A' is at least 1.0V lower than the battery voltage measured in
Step 2, replace cruise control module with modified part.
- If voltage difference between battery and terminal 'A' is within 1.0V, cruise control
unit has no problem.
- Verify repair.
|NC12 66 320
||Cruise Control Unit
- This informatoin applies to verified customer complains on vehicles covered under normal
warranty. Refer to the SRT microfiche for warranty term informaton.
|Warranty Type Code:
|Part No. Of Main Cause
||NC12 66 320
|Operation No./ Labor Hour:
||T0804XRX / 0.5
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