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 97' Thomas MVP-ER Speedometer dosen't work.
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msg1987
Active Member

16 Posts

Posted - 11/23/2012 :  11:31:22 AM  Show Profile  Visit msg1987's Homepage  Reply with Quote
I have an issue with my 97' Thomas MVP-ER speedometer. I have the Allison MD3060 transmission/5-speed, and push button shifter too. It's been on the fritz for a while now. It seems when the weather turns cold it won't work right. It will sometimes just randomly start working when I'm running over 45mph. But, then when I come to a stop it will go out again before 25mph. It seems like a loose wire somewhere but I don't know enough about it to check it out. Any help would be much appreciated!!

Thanks!!

Thomasbus24
Administrator

USA
3250 Posts

Posted - 11/24/2012 :  05:26:15 AM  Show Profile  Reply with Quote
Well, you may have a different setup than my two 97s had because you have that tranny. BUT...

Speedometers ran off of a sensor at the left front wheel. It sensed the passage of the inboard side of the brake drum (they had ridges cut into them). I had issues with dirt/grime buildup on the sensor from time to time. Also corrosion at its connections. It would be an easy starting point for you.

I would imagine if the tranny sensors drove the speedometer, and there were an issue there, that the tranny would be throwing fits. Is it working ok?
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Mechan1c
Top Member

USA
663 Posts

Posted - 11/26/2012 :  3:51:01 PM  Show Profile  Reply with Quote
About 18-24" up from where the above mentioned wheel speed sensor mounts, you will usually find a crappy butt-connect job on the 2 wires near where the split loom is anchored near the LH air can. When the zip ties finally break, the movement usually interupts the signal...
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msg1987
Active Member

16 Posts

Posted - 11/26/2012 :  4:29:07 PM  Show Profile  Visit msg1987's Homepage  Reply with Quote
Thanks Guys!! No problems with the tranny shifting or anything. Everything is fine. So, this speed sensor is on the front axle, left wheel brake drum? Is there wires coming off of it? I'll go look for something with wire coming off of it on the brake drum. I'll let you know.
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msg1987
Active Member

16 Posts

Posted - 11/26/2012 :  4:59:05 PM  Show Profile  Visit msg1987's Homepage  Reply with Quote


Is this what y'all are talking about?
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sob
Senior Member

USA
55 Posts

Posted - 11/28/2012 :  11:15:42 AM  Show Profile  Reply with Quote
Exactly. I know I'm jumping in here, yes that is the sensor for the speedo.

Another thing to check is the pulse dist. module.

Using a DVOM you can check the sensor. Set your meter to a/c voltage as IIRC and spin the wheel and look for a signal. If all checks good, move to the pulse dist. module and take a reading from there. On my 01's EF's its mounted underneath on the left front. It has 2 weather pack connectors and six wires that serve absolutley no purpose on the 01's. Disconnect the 2 wire connector hook up your DVOM and see if you get a signal.Module P.N. is 662202309. Speed sensor P.N. is 107824.

As others have said, connections give problems, the loom it's self breaks down and speed sensors go bad.

Having studied your picture, I'd look real hard at the sensor, looks like the wire insulation has shrunk back at the sensor, possibly grounding out. I ain't real wild about the looks of the connector either, disconnect it see if you have the green death thing going on. That sensor sets in a harsh enviroment.

If it turns out to be the sensor, get ready ! It will come hard, if it comes at all. If you pull the bracket off and decide to heat it up to get it loose, you will find that the sensor housing is aluminum and will melt quick but after it renders down it's easier to pick out of the threads of the bracket.
Disclaimer: All the info I have given you is about the fun I have had and is mostly based on an 01 MVP's. I have two westcoasters, that use a similar set up but do not use a pulse dist. module, they are a horse of a little different color.
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msg1987
Active Member

16 Posts

Posted - 11/28/2012 :  2:12:46 PM  Show Profile  Visit msg1987's Homepage  Reply with Quote
Ok, Thank you for your help!! So, from a very basic standpoint would you think it would be ok just for me to crimp new connectors on the wires and see if that helps? Then, if nothing still works try check the sensor with a multi-meter for signal? I can do all that but, I can't take the rim off right now because I don't have an air impact gun strong enough to break the lug nuts free. But, I'm getting there. lol
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sob
Senior Member

USA
55 Posts

Posted - 11/29/2012 :  04:14:10 AM  Show Profile  Reply with Quote
No need to remove the tire/rim, raise the vehicle. Cut your wire ties, unhook your connector and hook up your DVOM and spin the tire as fast as you can by hand and read the meter. Then move on from there.......
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msg1987
Active Member

16 Posts

Posted - 12/01/2012 :  12:08:34 PM  Show Profile  Visit msg1987's Homepage  Reply with Quote
Ok, I will do all that and see what happens. Also, last night when I took it for a drive I hit a big bump in the road and it started working for a few mins and then died again. Wonder if it's loose connections?
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sob
Senior Member

USA
55 Posts

Posted - 12/03/2012 :  03:49:25 AM  Show Profile  Reply with Quote
Loose connection/bad connection ? Very possible. Raise the front end, turn the key to the on position,spin the wheel while having someone watch the speedo all the while wiggling the harness. If it stars working, or at least jumping you will be close to your problem in the loom. As someone earlier suggested, remove the plastic shielding and see what you can see. Did you find a PDM ? If so what did the connections look like ? Thats if it has one, still not 100% sure your system has one.
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