WTF! no more overdrive!
#1
10-06-2009, 05:15 PM
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#2
10-06-2009, 05:55 PM
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#3
10-06-2009, 06:07 PM
if you want to shoot me a pm, i can answer this one w/o all the drama that shows up on here
#4
10-06-2009, 06:18 PM
+1 on the fuses. The overdrive unit is the only electronically controlled part of the transmission besides the TC lockup solenoid. So as long as the rest of the transmission is still working, its more than likely an electrical problem.
If the fuses are fine and your connectors are still attached, there's only one other thing I can think of. The computer won't shift the transmission into overdrive until the truck is up to temperature, so it could be a coolant temp sensor problem. I had my thermostat get stuck open one time and the truck never warmed up and would never shift into overdrive.
**EDIT**
Copied from the '95 FSM:
If the fuses are fine and your connectors are still attached, there's only one other thing I can think of. The computer won't shift the transmission into overdrive until the truck is up to temperature, so it could be a coolant temp sensor problem. I had my thermostat get stuck open one time and the truck never warmed up and would never shift into overdrive.
**EDIT**
Copied from the '95 FSM:
3-4 SHIFT SEQUENCE
Fourth gear overdrive operation is controlled by the
powertrain control module (PCM). The module operates
an overdrive solenoid on the valve body to cause
a 3-4 upshift. An overdrive switch, in the instrument
panel, allows the driver to select, or turn off the overdrive
feature. The switch must be in the ON position
before a 3-4 upshift will take place.
The overdrive switch does not operate the overdrive
solenoid directly. Instead, the switch acts as a
signal device that tells the PCM when overdrive has
either been selected, or turned off. When the switch
is turned On, the PCM records the signal; it then energizes
the overdrive solenoid when vehicle speed
and sensor inputs are at required levels.
Speed, temperature, and throttle position are
among the electrical signals supplied to the PCM to
operate the overdrive solenoid on the valve body. The
solenoid contains a check ball that opens and closes a
vent port in the 3-4 shift valve feed passage.
The overdrive solenoid and check ball are not energized
in first, second, third or reverse gear. The vent
port stays open diverting 2-3 valve line pressure
away from the 3-4 valve.
The overdrive solenoid is energized by the PCM.
The solenoid check ball closes the vent port when the
solenoid is energized. This allows line pressure from
the 2-3 shift valve to act directly on the 3-4 valve.
Line pressure on the 3-4 valve moves the valve to
upshift position. This exposes feed passages to the
3-4 timing valve, quick fill valve, 3-4 accumulator
and ultimately to the overdrive piston.
Line pressure through the timing valve moves the
overdrive piston into contact with the overdrive
clutch. The boost valve provides increased fluid apply
pressure to the overdrive clutch during the 3-4 upshift
and during fourth gear operation.
The overdrive piston engages the overdrive clutch
by pressing directly against the clutch pressure plate.
The overdrive clutch also disengages the direct clutch
during 3-4 upshifts.
As fluid pressure extends the overdrive piston, the
piston contacts the direct clutch hub pressing it rearward.
This action compresses the direct clutch spring
relieving spring load on the clutch pack. The clutch is
disengaged once spring load is relieved.
The 3-4 accumulator cushions overdrive clutch engagement
to smooth the transition into fourth gear.
The accumulator is charged at the same time as apply
pressure acts against the overdrive piston.
powertrain control module (PCM). The module operates
an overdrive solenoid on the valve body to cause
a 3-4 upshift. An overdrive switch, in the instrument
panel, allows the driver to select, or turn off the overdrive
feature. The switch must be in the ON position
before a 3-4 upshift will take place.
The overdrive switch does not operate the overdrive
solenoid directly. Instead, the switch acts as a
signal device that tells the PCM when overdrive has
either been selected, or turned off. When the switch
is turned On, the PCM records the signal; it then energizes
the overdrive solenoid when vehicle speed
and sensor inputs are at required levels.
Speed, temperature, and throttle position are
among the electrical signals supplied to the PCM to
operate the overdrive solenoid on the valve body. The
solenoid contains a check ball that opens and closes a
vent port in the 3-4 shift valve feed passage.
The overdrive solenoid and check ball are not energized
in first, second, third or reverse gear. The vent
port stays open diverting 2-3 valve line pressure
away from the 3-4 valve.
The overdrive solenoid is energized by the PCM.
The solenoid check ball closes the vent port when the
solenoid is energized. This allows line pressure from
the 2-3 shift valve to act directly on the 3-4 valve.
Line pressure on the 3-4 valve moves the valve to
upshift position. This exposes feed passages to the
3-4 timing valve, quick fill valve, 3-4 accumulator
and ultimately to the overdrive piston.
Line pressure through the timing valve moves the
overdrive piston into contact with the overdrive
clutch. The boost valve provides increased fluid apply
pressure to the overdrive clutch during the 3-4 upshift
and during fourth gear operation.
The overdrive piston engages the overdrive clutch
by pressing directly against the clutch pressure plate.
The overdrive clutch also disengages the direct clutch
during 3-4 upshifts.
As fluid pressure extends the overdrive piston, the
piston contacts the direct clutch hub pressing it rearward.
This action compresses the direct clutch spring
relieving spring load on the clutch pack. The clutch is
disengaged once spring load is relieved.
The 3-4 accumulator cushions overdrive clutch engagement
to smooth the transition into fourth gear.
The accumulator is charged at the same time as apply
Last edited by 95_318SLT; 10-06-2009 at 06:29 PM.
#5
10-06-2009, 06:19 PM
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#6
10-06-2009, 06:31 PM
If you have a problem with anyone on this forum, or any situation that arises, you need to inform a moderator or administrator. This is a public forum, people have differences of opinion and arguments will arise... it's inevitable. But we don't post answers just for the OP, we hope others will get help from the same problem, so please post the information you have in the thread in question so other people don't have to ask in the future.
Last edited by 95_318SLT; 10-06-2009 at 06:36 PM.
#7
10-06-2009, 06:47 PM
i don't like the arguments that constantly occur when offering sound advice with real life experiences however seems anytime i offer my advice it turns into drama. so if the op wants an alternative solution to all the computer electrical issues, i'll gladly offer some sound testing advice and step by step instructions as to how to repair this problem if it matches my description for diagnosis. id rather be pm'd first than me pm so i'm not wasting my time.
Last edited by shelbydaytona; 10-06-2009 at 06:51 PM.
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#8
10-11-2009, 07:39 AM
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#9
10-11-2009, 11:34 AM
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#10
10-11-2009, 09:36 PM
the 700r4 s-10 od trans dont have any vacuum controls. theres a bunch of stuff that can cause your od to not work but given the drama that shows up when trying to help, i'll do it thru pm's