over drive button
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Senior User
Joined: Jan 2010
Posts: 473
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From: dirty jerzy
over drive button
1990 7.3 auto 4x
a couple of things, the tack is not working.
the truck is not shifting -up-it 's like driving a manual
and last but not least
the botton on the dash for the overdrive is no longer working
any idea
a couple of things, the tack is not working.
the truck is not shifting -up-it 's like driving a manual
and last but not least
the botton on the dash for the overdrive is no longer working
any idea
Lead Driver
Joined: Mar 2006
Posts: 5,111
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From: western SD
I'm not an auto guy, but from what I have read hear the tach has to be working for the trans. to shift right. The tach sensor is the inch nut with two wires coming out of it on the front of the engine behind the oil fill spout. It is a dealer only item.
Postmaster
Joined: Apr 2008
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What Tom said - if the tach ain't working right the PCM will not know when to shift the trans, so it goes into this failsafe mode you're experiencing. Once you fix this issue, the OD switch may start working again.
Lead Driver
Joined: Nov 2003
Posts: 6,900
Likes: 3
From: Campbell River, B.C.
Check that power is getting to the PCM and that its getting from the PCM to the transmission. There may be a power break somewhere in the system.
Start by checking all your fuses, then scan for codes if the PCM is still getting power. Once you verify power to the PCM, check the electrical connection on the passenger side of the transmission (never use a screw driver to pull apart the connector or you will snap the locking tab).
Can you verify that you have 1st, 2nd and 3rd gears?
Start by checking all your fuses, then scan for codes if the PCM is still getting power. Once you verify power to the PCM, check the electrical connection on the passenger side of the transmission (never use a screw driver to pull apart the connector or you will snap the locking tab).
Can you verify that you have 1st, 2nd and 3rd gears?
Senior User
Joined: Jan 2009
Posts: 426
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From: Southwest Florida Coast
Go to
Silver State Ford Parts (Formerly DIRECTFORDPARTS.COM)Genuine Ford Truck Parts Lincoln Mercury Parts OEM Ford Parts and Accessories and search for
"OEM Catalog
SENSOR ASY-TACHOMETER"
It's about $50 and way cheaper than a dealer, good luck and welcome to the forum
Silver State Ford Parts (Formerly DIRECTFORDPARTS.COM)Genuine Ford Truck Parts Lincoln Mercury Parts OEM Ford Parts and Accessories and search for
"OEM Catalog
SENSOR ASY-TACHOMETER"
It's about $50 and way cheaper than a dealer, good luck and welcome to the forum
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
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Fleet Owner
Joined: Jul 2006
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From: Mi'kma'ki
oh yikes.
should this happen,is it safe to drive home,or you mean,don't go a hundred miles or anything?
should this happen,is it safe to drive home,or you mean,don't go a hundred miles or anything?
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Thread Starter
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Senior User
Joined: Jan 2010
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From: dirty jerzy
changed the tach sensor todady with one from junk yard , that made no differance, maybe that one was no good either, i guess i have no choise but bight the bullet and go to ford with$89& get a new one i checked the fuses under the dash ,they looked ok.
don't know what else to do
don't know what else to do
Lead Driver
Joined: Nov 2003
Posts: 6,900
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From: Campbell River, B.C.
Towing in limp mode a very bad idea because of how much slip there will be in starting off in 2nd gear. That can cause an overheat.
I've taken my truck around the block a few times and you simply have to be aware of what its doing. Its not an instant grenade situation and if you pay attention, it can be driven gently.
New User
Joined: Dec 2009
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Did you check for chaffing of the OD wire under the plastic steering cover. It's been know to short out and you can crank all day long and your vehicle won't start. Just fixed mine last month with no reoccuring problems.
Postmaster
Joined: Apr 2008
Posts: 4,802
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His truck has the OD cancel button on the dash, not on the shifter like yours, and there ain't much around in that general area that could cut the harness insulation. Not to mention the whole dash is plastic, so for the most part there ain't nothing the wires can ground on too.
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Senior User
Joined: Jan 2010
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From: dirty jerzy
m.l.s.c. is there any way to test the tach- it self? when i pulled the cluster out i cleaned the film connection & the plug connectors with elc con. spray.but that is all i did can i some how give it power to see if it is working? i've been throwing parts at it all over ¬hing--- this has been two weeks
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
Joe, one thing to consider.
Unless the dash tach is somehow sending a signal back to the computer for the tranny, I don't think a bad gauge is your problem.
The computer is reading the signal from the tach sensor, not the gauge.
So I think your OD light blinking is a bad connection somewhere between the tach sensor and the tranny computer.
I think the signal at the computer splits to drive the dash gauge.
I am flying in the dark on this since i have never looked at how that works on an IDI E4OD though.
Since you are in limp mode, the tranny computer is not getting the signal from the tach sensor.
If it runs like I think it does, then there is no way the dash gauge could work.
If all your connections are in good shape, then I would be looking for a broken wire between the tach sensor and the computer.
Unless the dash tach is somehow sending a signal back to the computer for the tranny, I don't think a bad gauge is your problem.
The computer is reading the signal from the tach sensor, not the gauge.
So I think your OD light blinking is a bad connection somewhere between the tach sensor and the tranny computer.
I think the signal at the computer splits to drive the dash gauge.
I am flying in the dark on this since i have never looked at how that works on an IDI E4OD though.
Since you are in limp mode, the tranny computer is not getting the signal from the tach sensor.
If it runs like I think it does, then there is no way the dash gauge could work.
If all your connections are in good shape, then I would be looking for a broken wire between the tach sensor and the computer.