P0500 code and speedometer doesn't work.

[Geezer000]

So my speedometer finally stopped working after flickering on and off for a month and it through a code P0500. I know that the speedo gets its signal from the front ABS sensors but both check out fine and I also checked the wires that go to the ABS HU/CM. My last chance to fix the issue is the wire from the ABS HU/CM to the main computer but I have no idea which one it is. I thought it might be wire 58 on the computer but that leads to the dash not out to the ABS HU/CM. Is there a different speed sensor that I don't know about? Anybody else have this issue? Thoughts?

 

[Geezer000]

So I checked for voltage at the 3O terminal of my Instrument cluster which is for the Speedometer and I got 5 volts which I guess means the my speedo is getting power or is that the signal? I wouldn't think so because it would be a variable voltage that causes the speedo to show speed wouldn't it. Is that terminal just for the power to the speedo or does that also contribute to the speed signal? I think I'm a little over my head...... Anybody know what wire is the signal wire?

 

[Geezer000]

Is there an actual vehicle speed sensor on an ABS 2003 Protege or all the service manuals just generic including the VSS?

 

[Geezer000]

Ok...... I now know that the only signal the speedo gets is from the Q output of the ABS HU/CM but which cable is it going into the speedo? The speedo gets no signal from the PCM from pin 58 because I believe that is only from NON-ABS Proteges. That pin supplies 5v's to the speedo. Anybody know which wire is the signal wire from the ABD HU/CM to the Speedo? I have all the wiring diagrams but I can't find the proper wire. Can anybody read those properly?

 

[mazdaspeedp]

i would check the rear wheel speed sensor or abs sensor i think its called. i remember allot of the right rear sensors going bad on msps when i seen them at mazda. Is your abs light on?

 

[Geezer000]

i would check the rear wheel speed sensor or abs sensor i think its called. i remember allot of the right rear sensors going bad on msps when i seen them at mazda. Is your abs light on?

My ABS and brake light are on and my speedo doesn't work. I thought only the front ABS sensors were required for speedo operation?

 

[Geezer000]

So i've done more troubleshooting and it seems that the "Z" terminal on my ABD HU/CM connector is not getting any power. I know that the ABS has a constant source of power from the battery going through the 60a fuse in the fuse block but the "Z" goes through the firewall to the (engine 10a fuse). Somewhere in between the connector and the fuse box its losing all power. Anybody now which connectors to look at?

 

[Tuners and Rods]

This car has a speed sensor in the Trans

 

[Geezer000]

This car has a speed sensor in the Trans

Any 2003 protege with ABS senses the speed via the front ABS sensors. There are no speed sensors. The ABS sensors go into the ABS HU/CM which then sends the signal DIRECTLY to the speedo in the instrument cluster. Any protege without ABS has a speed sensor that sends signal to the PCM which then sends to the Instrument cluster. Believe when I say i have thoroughly researched this for a week to try and diagnose the problem.

 

[Geezer000]

Well I found the problem sort of. I figured since I have no power to the "Z" connection of the ABS HU/CM so I found that its supposed to be a blk/blu wire going from it to the fuse box. There are 4 bloody BLK/BLU wires that go to the fuse box so I just bypassed it and rewired a secondary 12v switched wire to the ABS HU/CM and PRESTO it's done!!!! What a long week.
Thanks everyone for following my story. If anyone else has any problems with the ABS or speedo let me know since I feel like a master now lol.

 

[Tuners and Rods]

They also have a speed sensor in the trans. Which in my case causes a nasty leak when the seal goes bad.

 

[Geezer000]

They also have a speed sensor in the trans. Which in my case causes a nasty leak when the seal goes bad.

You mean one of those two plugs in the tranny with green wires? I have no idea what those are.....

EDIT: I believe one is a Neutral switch and the other is the back up light switch.

 

[Tuners and Rods]

Neutral switch is behind the clutch pedal