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Formerly F350_Beast
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Discussion Starter #1
Finally got the damn thing to stop blinking. My fire chief who is a powerstroke technician did a scan on my truck with his snazzy snap on scanner and the tranny was throwin a code talkin about the torque converter slipping. It also said the MAP sensor was bad. Because my fire chief is a bad ***, he happend to have a brand new MAP sensor in his truck. So we popped it in and so far everything is great. He said if it starts blinking again that we would have to put in a new torque converter. Just wanted to share this info with you guys, thanks for all the help!
 

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Found On Russ' Drive
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F350_Beast said:
Finally got the damn thing to stop blinking. My fire chief who is a powerstroke technician did a scan on my truck with his snazzy snap on scanner and the tranny was throwin a code talkin about the torque converter slipping. It also said the MAP sensor was bad. Because my fire chief is a bad ***, he happend to have a brand new MAP sensor in his truck. So we popped it in and so far everything is great. He said if it starts blinking again that we would have to put in a new torque converter. Just wanted to share this info with you guys, thanks for all the help!
He may be right. There actually is no sensor that can determine torque converter slip. The code was revised to transmission slip. Basically the code is generated when the PCM inputs from engine and axle don't match. Since the transmission is between them, it gets the blame.

A bad Map/Baro sensor would affect fuel mixture, which also affects rpm and speed. Hopefully it was a hard fault, with the OD light blinking constantly not just sometimes. Those type of sensor failures are the most straight forward to repair. The converter/transmission code slip is an educated guess at best.



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My truck the OD light has been flashing on and off also. When the light is flashing the tranny shifts hard. the tranny is shifting fine in all gears and if i push the OD switch it still kicks out of overdrive fine. Then the light stops flashing the tranny shifts smooth.?????? any idea would would cause this.???

it has been doing this off and on for about a month now.
 

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Formerly F350_Beast
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zippar said:
My truck the OD light has been flashing on and off also. When the light is flashing the tranny shifts hard. the tranny is shifting fine in all gears and if i push the OD switch it still kicks out of overdrive fine. Then the light stops flashing the tranny shifts smooth.?????? any idea would would cause this.???

it has been doing this off and on for about a month now.
try what i did...replace the map sensor. either that or it could be a speed sensor (in the rear diff.) have you had it scanned for codes yet?
 

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when my brother had a 97 the flashing OD light was a warning that his tranny was going, it did this every time it ate a tranny...BTW it went though 6 in 3 months.
 

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zippar said:
My truck the OD light has been flashing on and off also. When the light is flashing the tranny shifts hard. the tranny is shifting fine in all gears and if i push the OD switch it still kicks out of overdrive fine. Then the light stops flashing the tranny shifts smooth.?????? any idea would would cause this.???

it has been doing this off and on for about a month now.
The light and hard shift are related. Hard shift happens in fail safe mode. A shift strategy that is adaptive when the pcm detects a fault and flashes the light. Line pressure is raised to allow you to drive for service and have the service code read. Raised LP causes the hard shift.
I recommend you have the code(s) read first. There are many. 1 is tranny overheat. You have a tranny temp sensor on board. The best course is to know the codes meaning and if it's valid or a byproduct of another code before buying parts.


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Mine is doing the same thing. when my buddy read the codes he told me it was the torque converter lockup sylenoid (sp). Anyone had this, I am going to replace it and see if that fixes the problem.
 

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make sure there is no water in the weather pack connecter where the body harness for the transmission plugs into the side of the tranny, that will cause all kinds of fun!
 

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Definately get the codes read before throwing parts at it..

In my experience the O/D flashed when the PCM got "Upset" about a shift. 2 months after it started doing this I ended up at John Wood for a complete rebuild as it was smoked!
 

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Power Stroke said:
make sure there is no water in the weather pack connecter where the body harness for the transmission plugs into the side of the tranny, that will cause all kinds of fun!
:Thumbup: :Thumbup: :Thumbup: The OD and CEL warning light system was mean't for a human to diagnosis and interept. It depends on the correct function of the other sensors and wiring harness connections and grounds. Water, magnetic fields, resistance, loose pins, Bat volts, corrosion and etc. can all drive it bananas--and the mechanic. LOL
I have seen both transmission and converter replaced to try and stop a blinking light and trucks sold because of it before.
No offense, but even the 2008 Fords or other brands won't have a system that can detect a bad part by code #. A code is a clue where to begin troubleshooting many times if it's not a hard fault.
It's takes a dozen engineers to turn something a $25 cable can do, into an electronic control. :roflmao: You always know what's wrong when a cable breaks. :D And it's not a big hit to the wallet. Controlling air and fuel mixtures/ratios--electronics is best and most accurate. Other components--no. And thats the way it is and my :2cents.



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F350_Beast said:
try what i did...replace the map sensor. either that or it could be a speed sensor (in the rear diff.) have you had it scanned for codes yet?
It may be the MAP SENSOR where is that located.?

Not sure about this but a buddy told me if its the speed sensor the speedo stops working is this true.?
 

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Formerly F350_Beast
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Discussion Starter #13
Well I spoke too soon. Damn light started blinking again. Gonna put the spare tranny in. Woooo
 

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Discussion Starter #14
zippar said:
It may be the MAP SENSOR where is that located.?

Not sure about this but a buddy told me if its the speed sensor the speedo stops working is this true.?
The MAP sensor is on the passenger side firewall inside the engine bay.

Here's a pic:
 

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On my 96 F450 the OD Light began flashing. Never could find out the meaning behind it. Well two weeks ago I just replaced the TC and flywheel. One morning the truck sounded like it had dropped a rod at idle. It wasn't until the engine hit 1500rpm the noise quit. I had two shops tell me I blew the motor:pointlaugh. Thanks to this board I had an idea it was the TC. Come to find out the flywheel had separated in two pieces. Breaking off in a complete circle leaving the bolts attached.
 

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Another sign a trans is going bad is if it will just die when put into gear. or almost stall the truck when put in gear. My buddies 97 did that. Turned out the seals were junk on the trans, and the TC.

That blinking OD light can mean anything with these trucks!

zippar said:
Not sure about this but a buddy told me if its the speed sensor the speedo stops working is this true.?
More than likely it will Jump. can hold a steady speed, say 50mph, then jump to 60mph, then down to 40mph, then back to 50mph and stay there.

Sometimes it wont give you a reading at all, and just jump, or it could fail totally and not work, giving you NO speedometer.

Its unlikely for a VSS to just go bad unless you have something floating in the diff oil, or something broken in the rear end, but it has happened. I went through a differential, cover, exciter ring, and VSS sensor when my other truck grenaded the spider gears. the hint somethin was was wrong was the jumping speedo. I had a peice of gear still in the diff floating, and it caught the exciter ring and ate the diff cover and ring.

Exciter ring is what tells you how fast your going, it bolts onto the ring gear on the differential.
 
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