Exciter Ring

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Dec 9, 2004 | 08:22 AM

alz

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Fleet Mechanic

Joined: Nov 2004

Posts: 1,324

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From: Michigan

Exciter Ring

95 f150.
Been chasing a speedo problem and narrowed it to the exciter ring/sensor. Replaced the RABS sensor twice. Visually there's nothing wrong with the ring, but I had a scope on it the other day and was getting a spike about every 80 milsec. Since the PSOM only samples this output the speedo does not jump all the time, but is annoying enough when using the cruise. Does anyone have any suggestions as to how to check the runout on the tone ring. Either throuh the RABS hole or with the diff cover removed?

Dec 9, 2004 | 08:27 AM

Racerguy

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Joined: Aug 2002

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From: BC, Canada

A bit of runout shouldn't cause the problem. A more likely cause would be a crack in the ring. You can check for that through the sensor hole but it's easier with the cover off.

Dec 9, 2004 | 12:36 PM

alz

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Fleet Mechanic

Joined: Nov 2004

Posts: 1,324

Likes: 4

From: Michigan

I've had the diff open twice and visually inspected the ring and all teeth. Would I be able to see a crack? All teeth are present and accounted for. On the scope I get a spike of voltage up to 5 and then down to about 3, then goes back to 4.5. This happens about every 80 milsecs. Any other suggestions?

Dec 9, 2004 | 09:37 PM

Racerguy

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Joined: Aug 2002

Posts: 12,679

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From: BC, Canada

A cracked ring can be pretty hard to see. You have to look very closely. If it's cracked then the distance between 2 teeth will be off a bit and could maybe cause your problem.
I've never had a scope on one of these so I'm not sure exactly what the pattern would look like.