E4OD / Tach Sensor / Electrical Issue
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Freshman User
Joined: Oct 2005
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From: Alaska
E4OD / Tach Sensor / Electrical Issue
I have a 1994 F250 IDI w/ E4OD tranny (shop rebuilt about 1 year ago) - throttle position sensor replaced at time of rebuild.
A couple of months after the rebuild my speedo and tach would "drop out" briefly while driving which would affect the tranny. I quickly replaced the speed sensor and the tach sensor as I didn't want to harm the tranny ($2800 rebuild).
The tach has worked worked 98% of the time until recently when the tach started acting up again - the tach "drops out" (stops working or reads much lower for a split second) which causes the tranny to shift/act funny. The speedo stills works OK (a bit of a jiggle in the needle (1 mph or so) but works continuously)
I fugure it's probably an electrcial connection or ?? (other ideas). Any idea of which connection or where to start?
Thanks
A couple of months after the rebuild my speedo and tach would "drop out" briefly while driving which would affect the tranny. I quickly replaced the speed sensor and the tach sensor as I didn't want to harm the tranny ($2800 rebuild).
The tach has worked worked 98% of the time until recently when the tach started acting up again - the tach "drops out" (stops working or reads much lower for a split second) which causes the tranny to shift/act funny. The speedo stills works OK (a bit of a jiggle in the needle (1 mph or so) but works continuously)
I fugure it's probably an electrcial connection or ?? (other ideas). Any idea of which connection or where to start?
Thanks
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
I heard of one guy who simply pulled out his cluster and reinstalled it, that minor disturbance was enough to fix the problem with the tach and transmission, might want to put some dielectric grease in there while your at it.
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
A dead tach sender should/would send the automatic trans into a "failure management mode" (limp mode) with harsh engagements and firm shift feel and an abnormal shift schedule. It has no effect on a manual trans only the Tach readings.
Check the wires where they exit the big nut on the oil filler housing , known to short out due to bare wire.....
Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50. You can remove and clean it but usually changed later too.
You can test it too, hold it in the air away from ferrous metal, using an ohm meter lead on each wire you need DC resistance between 2000-3000 ohms.
Check the wires where they exit the big nut on the oil filler housing , known to short out due to bare wire.....
Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50. You can remove and clean it but usually changed later too.
You can test it too, hold it in the air away from ferrous metal, using an ohm meter lead on each wire you need DC resistance between 2000-3000 ohms.
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Freshman User
Joined: Oct 2005
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From: Alaska
PLC - I replaced the tach sensor a few months ago - it worked fine until recently.
This morning I unplugged the pass side fenderwell connections - they looked good and clean, no corrosion - still had dielectric grease in them......drove to it work - no tach/tranny issues I guess I'll have to wait to see if it happens again.
I called the tranny shop to see if they could check trouble codes for me - they said the 1994 has a "soft memory" (OD light flashing) - when you turn the key off the trouble code goes away - no longterm memory. I basically have to drive it to the shop when it happens and don't shut off the motor......does that sound right?....seems to me code should stay a while.
This morning I unplugged the pass side fenderwell connections - they looked good and clean, no corrosion - still had dielectric grease in them......drove to it work - no tach/tranny issues I guess I'll have to wait to see if it happens again.
I called the tranny shop to see if they could check trouble codes for me - they said the 1994 has a "soft memory" (OD light flashing) - when you turn the key off the trouble code goes away - no longterm memory. I basically have to drive it to the shop when it happens and don't shut off the motor......does that sound right?....seems to me code should stay a while.
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
For about $30 you can get an OBD1 code reader at Wallymart and do your own code reading..... Yes there are hard and soft codes......some will eliminate themselves after several starts others do not. Azone has a code reader use for free...... actually they will do for you.
Senior User
Joined: May 2006
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check all of your Ground Wires, it is very important that they make good contact. There should be one from the trany to frame make sure it is clean. Water in the connector at the trany could also cause the problem. I now regreese my tranny connector every time I change the Motor Oil. The to ground conections are just as important as the Power connections, with out a clear path to ground it will not see the correct power.
Hope this helps ,
Ken H
Hope this helps ,
Ken H
