O/D off
#1
07-22-2011, 05:59 PM
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#4
07-22-2011, 10:43 PM
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#5
07-22-2011, 11:42 PM
#6
07-23-2011, 07:31 AM
when the light if on, then the OD is off, and your transmission will shift one less time, and you'll have more pulling power at that in-between speed of 45-55.
when the light is off, then the transmission will shift one more time into overdrive. this will provide better MPG and lower engine RPM, but less pulling power. i'm not sure about your 94, but it might shift into OD at somewhere in the 45-55 mph range. if you have a tach, you'll notice about a 500 rpm drop. to further confuse the issue, you will also feel/see what looks like another shift, but its not - its the torque converter clutch lockup. on my 01, this is another 300 rpm drop on the tach.
again i don't know about your 94, but on my 01 46RE, depending on pcm software version, the TCC lockup can still occur with OD off (or not).
in general -
if you are towing or heavily loaded - turn OD off.
if you are driving in town at 45-50 and the truck feels sluggish, or is shifting in/out of OD a lot - turn OD off.
if you are on the highway running 55+ (and not towing), turn OD on.
when the light is off, then the transmission will shift one more time into overdrive. this will provide better MPG and lower engine RPM, but less pulling power. i'm not sure about your 94, but it might shift into OD at somewhere in the 45-55 mph range. if you have a tach, you'll notice about a 500 rpm drop. to further confuse the issue, you will also feel/see what looks like another shift, but its not - its the torque converter clutch lockup. on my 01, this is another 300 rpm drop on the tach.
again i don't know about your 94, but on my 01 46RE, depending on pcm software version, the TCC lockup can still occur with OD off (or not).
in general -
if you are towing or heavily loaded - turn OD off.
if you are driving in town at 45-50 and the truck feels sluggish, or is shifting in/out of OD a lot - turn OD off.
if you are on the highway running 55+ (and not towing), turn OD on.
#7
02-17-2016, 06:36 AM
Default O/D to off
Is there a way to default to O/D off?
when the light if on, then the OD is off, and your transmission will shift one less time, and you'll have more pulling power at that in-between speed of 45-55.
when the light is off, then the transmission will shift one more time into overdrive. this will provide better MPG and lower engine RPM, but less pulling power. i'm not sure about your 94, but it might shift into OD at somewhere in the 45-55 mph range. if you have a tach, you'll notice about a 500 rpm drop. to further confuse the issue, you will also feel/see what looks like another shift, but its not - its the torque converter clutch lockup. on my 01, this is another 300 rpm drop on the tach.
again i don't know about your 94, but on my 01 46RE, depending on pcm software version, the TCC lockup can still occur with OD off (or not).
in general -
if you are towing or heavily loaded - turn OD off.
if you are driving in town at 45-50 and the truck feels sluggish, or is shifting in/out of OD a lot - turn OD off.
if you are on the highway running 55+ (and not towing), turn OD on.
when the light is off, then the transmission will shift one more time into overdrive. this will provide better MPG and lower engine RPM, but less pulling power. i'm not sure about your 94, but it might shift into OD at somewhere in the 45-55 mph range. if you have a tach, you'll notice about a 500 rpm drop. to further confuse the issue, you will also feel/see what looks like another shift, but its not - its the torque converter clutch lockup. on my 01, this is another 300 rpm drop on the tach.
again i don't know about your 94, but on my 01 46RE, depending on pcm software version, the TCC lockup can still occur with OD off (or not).
in general -
if you are towing or heavily loaded - turn OD off.
if you are driving in town at 45-50 and the truck feels sluggish, or is shifting in/out of OD a lot - turn OD off.
if you are on the highway running 55+ (and not towing), turn OD on.
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#8
02-17-2016, 09:40 AM
Yup. There is even a write-up for it in the DIY/FAQ section here. O/D off switch is just a momentary switch, that sends a signal to the PCM. Using a relay triggered by the ignition switch in the start position will send the signal. O/D defaults to off. 
#9
05-27-2021, 11:16 AM
#10
05-27-2021, 02:04 PM
