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Diesel Maniac
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110 Posts
Discussion Starter #1
I just found out there isn't an obd port on my 1993 f350 7.3. All gauges work just fine, don't have a speedo. Any suggestions
 

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Junior Member
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22 Posts
Re speedo

You have a connector under the hood but this is OBD 1,no help for speedo.Think you have a speedo cable,if so you can remove cable from peedo gear in trans and take a drill and spin cable while someone looks to see if needle moves up.if it's a electric motor for the speedo in the cluster,you will also have a speedo sensor in the transmission tail stock witch is a input signal for speedo motor in the cluster(dash).you can check plug for corroded connection on the speedo sensor.Question to help more,was the speedo bouncing or just quit.
 

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Junior Member
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22 Posts
Re speedo

So if that's the case you then have a speed sensor at the rear side of the the transmission (tail stock).This sensor changes mechanical to electrical signal to the cluster speedometer.it could be one or the other.Question? Did the speedo just stop working or did the speed seem to fast compared to the speed you thought you were going.If so it sounds like the speedo in the cluster.Also check while driving if the odometer(mileage) is working.If not,it's the speedo in the cluster.If both speedo and odometer is not working,suspect speedo sensor in the rear side of transmission is at fault or electrical plug
 

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Diesel Maniac
Joined
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110 Posts
Discussion Starter #5
The speedo and odometer both don't work at all. All gauges work. The sensor is in the rear end. I changed that.. By not having a PCM it is real hard. I am beginning to think that the speedo itself is bad. In the 92 and 93 are different setup than all the 7.3's. They are old school electronics
 

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Aimless Wanderer
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929 Posts
The speedo and odometer both don't work at all. All gauges work. The sensor is in the rear end. I changed that.. By not having a PCM it is real hard. I am beginning to think that the speedo itself is bad. In the 92 and 93 are different setup than all the 7.3's. They are old school electronics
The sensor in the rear axle housing has nothing to do with the speedometer. It is the inductive pickup for the rear anti lock brakes if I remember correctly. The speedo is driven at the transmission output shaft as Mr. Sanford has referenced. There will be an electrical module and plug a few inches forward of the rear of the transmission on the left side tail housing. These do fail from time to time.
 

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Diesel Maniac
Joined
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110 Posts
Discussion Starter #12
So if that's the case you then have a speed sensor at the rear side of the the transmission (tail stock).This sensor changes mechanical to electrical signal to the cluster speedometer.it could be one or the other.Question? Did the speedo just stop working or did the speed seem to fast compared to the speed you thought you were going.If so it sounds like the speedo in the cluster.Also check while driving if the odometer(mileage) is working.If not,it's the speedo in the cluster.If both speedo and odometer is not working,suspect speedo sensor in the rear side of transmission is at fault or electrical plug
Thanks Marc, you were right, I was misinformed, way to goooooooo.......
 

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Diesel Maniac
Joined
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110 Posts
Discussion Starter #15
No rear sensor in tranny, the hole has never been cut out and the wire has a factory cap. Come to find out it is combo abs/speed sensor in rear end. I have one ordered and hope it don't get back ordered
 

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Aimless Wanderer
Joined
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929 Posts
No rear sensor in tranny, the hole has never been cut out and the wire has a factory cap. Come to find out it is combo abs/speed sensor in rear end. I have one ordered and hope it don't get back ordered
You must have a late production 93, or the rear axle has been changed as the combination sensor was incorporated in the 1994 and later models; I do not remember ever seeing a 1993 model with this setup. Anything is possible however as the OEM's gear for a new production order.
 

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Diesel Maniac
Joined
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110 Posts
Discussion Starter #19
Update... Cruise, speedometer, odometer all fixed
10/93 f350 5spd std. 7.3 IDI n/turbo dually
Abs/speed sensor in rear end
Aftermarket part
Now working on power to heater/ac fan

Thanks to everyone
 
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