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Ford Racing Speedometer Recalibration Tool ('99-'04) - Installation Instructions

Installation Time

60 minutes

American Muscle
Shop Parts in this Guide


Installation on 1999-2004 Mustang:

1. Identify and disconnect the Output Shaft Speed (OSS) connector from the transmission.

2. Identify the OSS ( ) signal output wire. The wire colors are typically GREEN/WHITE on the OSS ( ) signal side, and GRAY/RED on the OSS (-) return side. Remove the harness wrap to expose approximately 6 inches of the OSS wire leads, and cut the GREEN/WHITE signal wire, insuring that there is enough wire remaining on each side to splice in the wires coming from Speed-Dial.

3. Once the GREEN/WHITE OSS ( ) signal wire has been cut, attach the GREEN wire from Speed-Dial to the GREEN/WHITE cut wire coming FROM the transmission. The GREEN wire on Speed-Dial is the SIGNAL IN.

4. Now attach the WHITE wire from Speed-Dial to the remaining GREEN/WHITE cut wire which leads INTO the vehicle harness. The WHITE wire on Speed-Dial is the SIGNAL OUT.

5. Splice the RED wire (using solder and heat shrink) from Speed-Dial to a 12V KEY-ON voltage source. This RED wire should have voltage ONLY when the ignition key is in the 'RUN' position.

6. Finally, attach the BLACK wire from Speed-Dial to a ground source.

Note:For best results, this ground source should be checked for continuity to the negative side of the battery. An optimum ground path should measure less than 0.5 ohms to the negative battery post. (When measuring resistance, always make sure the key is in the OFF position.)

Alternate Installation for Underhood Applications in 1999-2004 Mustang

1. For under hood installation on a 1999 to 2004 Mustang, the VSS ( ) signal wire can also be found at the right rear of the engine compartment in the black 16-Pin connector.

2. In the 16 pin connector, identify circuit 970, which should be a GREEN/WHITE wire in cavity 15. This is the OSS ( ) signal wire. Use the procedure listed above for installation on this wire. To insure you are working with the correct wire, you should verify continuity to the OSS ( ) wire at the transmission BEFORE CUTTING THIS WIRE!

3. You may also use circuit 391 as the 12V Key-On Source. This should be a RED/YELLOW wire located in cavity 5. Once again, you should verify that this is the correct wire BEFORE splicing into it!

Speed Setting Procedure

Installation instructions provided by Ford Racing

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