Time delay control module
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The TDCM function is described in the TM1591 as it relates to the 332 tractors. It controls the fuel shutoff valve to stop the engine if the safety circuits detect a dangerous condition such as the operator leaving the seat when the tractor is out of neutral or the PTO is engaged. It also controls the power to the PTO relative to these same safety constraints.
Look in section 240-15 of the manual for details...
Chuck
Look in section 240-15 of the manual for details...
Chuck
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Hello S Keating
Chuck is correct I call it the Engine safety Brain of the wiring system. Regards, Kurt
Chuck is correct I call it the Engine safety Brain of the wiring system. Regards, Kurt
Joined
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5,085 Posts
the solenoid can go bad and you can bench test it with 12v
first hold it in manually and turn key on, does it hold? and do you get power to it?
is it the 2 or 3 wire one?
3 wire has a start high current and hold low current winding
first hold it in manually and turn key on, does it hold? and do you get power to it?
is it the 2 or 3 wire one?
3 wire has a start high current and hold low current winding
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10,553 Posts
Caution on the three wire version as the "pull in" winding is not meant to be powered for long periods of time and will overheat and burn out... The TDCM ensures that the pull in winding is pulsed for only a few seconds. Quoting from the manual, the two wire works like this:
The function of the fuel shutoff solenoid circuit is to
stop engine operation by shutting off fuel flow to the
fuel injector pump. This is accomplished either
manually using the key switch or automatically when
the operator rises from the seat for more than one
second with machine in gear or PTO engaged.
OPERATOR ON SEAT—MACHINE IN GEAR
AND/OR PTO ENGAGED:
The normally open contacts of seat switch (S6) close
when the operator sits on the seat. When the key
switch (S1) is turned to the RUN or START position,
current flows from the positive (+) terminal of battery
(G1), through fusible link (F4) to terminal “B” of the
key switch. Current flows across the key switch
contacts to terminal “BR”. From terminal “BR”,
currrent flows to 25-amp fuse (F1) and 10-amp fuse
(F2). From fuse (F2), current flows across the closed
contacts of the seat switch to pin “9” of TDC module
2-pin connector (X14).
Inside the TDC module, current flows through seat
time delay integrated circuit (IC) (E), then to seat time
delay transistor (D). As long as current from the time
delay IC flows to the transistor, the transistor is
“switched on”. In this state, the transistor completes
the path to ground for fuel shut-off relay coil (B). The
ground path allows current to flow from fuse (F1) to
pin “3” of the TDC module 8-pin connector (X13).
Inside the TDC module, current flows through the fuel
shut-off relay coil to ground. This energizes the relay
coil which closes fuel shut-off relay contacts (A).
Current from fuse (F1) then flows across the relay
contacts and out pin “2” of 8-pin connector (X13).
From pin “2”, current flows to fuel shutoff solenoid
(Y3). From solenoid (Y3), current flows through 8-amp
circuit breaker (F5) to ground, energizing the
solenoid. The energized solenoid moves the fuel
shutoff linkage to the ON position. This opens a valve
and allows fuel to flow into the fuel injector pump.
When the operator rises from the seat, the seat
switch contacts open, causing current to stop flowing
to the seat time delay IC. If the operator does not
return to the seat within approximately one second,
the time delay IC stops current flow to transistor (D).
The transistor will “switch off”, causing current through
the fuel shut-off relay coil to stop flowing, which
opens the fuel shutoff relay contacts. The open relay
contacts stops current flow to the fuel shutoff
solenoid, de-energizing the solenoid. The
de-energized solenoid moves the fuel shutoff linkage
to the OFF position. This shuts off the fuel flow, thus
stopping the engine.
NOTE: Driving the machine over rough terrain can
cause the seat switch contacts to momentarily
open and close. If this happens, the seat time
delay IC delays the opening of fuel shutoff
relay contacts (A), which allows the engine to
operate without interruption.
If the operator returns to the seat within
approximately one second, current flow is
re-established to the time delay IC before it has a
chance to “time out” and stop current flow to the
transistor. Current flow is NOT interrupted to the fuel
shutoff solenoid, allowing the engine to continue
operating.
OPERATOR OFF SEAT—MACHINE IN NEUTRAL
AND PTO DISENGAGED:
When operator is off the seat, current to the fuel
shutoff solenoid can still be maintained through the
interlock circuit. For current to flow through the
interlock circuit, the key switch must be turned to the
RUN or START position, the hydrostatic control lever
in the N/STOP position, and PTO switch(es) in the
OFF position (PTO disengaged).
With these conditions met, current flows from fuse
(F1) through the interlock contacts of the PTO
switches, transmission neutral switch, to pin “7” of
TDC module 8-pin connector (X13). Inside the TDC
module, current flows from pin “7” to fuel shut-off
transistor (C). As long as current from the interlock
circuit flows to transistor (C), the transistor is
“switched on”. In this state, the transistor provides an
alternate path to ground for the fuel shut-off relay
coil. The fuel shutoff relay contacts close, allowing
current to flow to the fuel shutoff solenoid.
The 25-amp fuse (F1) and 10-amp fuse (F2) protect
the fuel shutoff circuit from excessive current.
The 8-amp circuit breaker (F5) disables the start
circuit and fuel shutoff solenoid (solenoid will not
energize) if breaker is tripped.
Due to post size limits the three wire version manual text needs to be in my next post....
Chuck
The function of the fuel shutoff solenoid circuit is to
stop engine operation by shutting off fuel flow to the
fuel injector pump. This is accomplished either
manually using the key switch or automatically when
the operator rises from the seat for more than one
second with machine in gear or PTO engaged.
OPERATOR ON SEAT—MACHINE IN GEAR
AND/OR PTO ENGAGED:
The normally open contacts of seat switch (S6) close
when the operator sits on the seat. When the key
switch (S1) is turned to the RUN or START position,
current flows from the positive (+) terminal of battery
(G1), through fusible link (F4) to terminal “B” of the
key switch. Current flows across the key switch
contacts to terminal “BR”. From terminal “BR”,
currrent flows to 25-amp fuse (F1) and 10-amp fuse
(F2). From fuse (F2), current flows across the closed
contacts of the seat switch to pin “9” of TDC module
2-pin connector (X14).
Inside the TDC module, current flows through seat
time delay integrated circuit (IC) (E), then to seat time
delay transistor (D). As long as current from the time
delay IC flows to the transistor, the transistor is
“switched on”. In this state, the transistor completes
the path to ground for fuel shut-off relay coil (B). The
ground path allows current to flow from fuse (F1) to
pin “3” of the TDC module 8-pin connector (X13).
Inside the TDC module, current flows through the fuel
shut-off relay coil to ground. This energizes the relay
coil which closes fuel shut-off relay contacts (A).
Current from fuse (F1) then flows across the relay
contacts and out pin “2” of 8-pin connector (X13).
From pin “2”, current flows to fuel shutoff solenoid
(Y3). From solenoid (Y3), current flows through 8-amp
circuit breaker (F5) to ground, energizing the
solenoid. The energized solenoid moves the fuel
shutoff linkage to the ON position. This opens a valve
and allows fuel to flow into the fuel injector pump.
When the operator rises from the seat, the seat
switch contacts open, causing current to stop flowing
to the seat time delay IC. If the operator does not
return to the seat within approximately one second,
the time delay IC stops current flow to transistor (D).
The transistor will “switch off”, causing current through
the fuel shut-off relay coil to stop flowing, which
opens the fuel shutoff relay contacts. The open relay
contacts stops current flow to the fuel shutoff
solenoid, de-energizing the solenoid. The
de-energized solenoid moves the fuel shutoff linkage
to the OFF position. This shuts off the fuel flow, thus
stopping the engine.
NOTE: Driving the machine over rough terrain can
cause the seat switch contacts to momentarily
open and close. If this happens, the seat time
delay IC delays the opening of fuel shutoff
relay contacts (A), which allows the engine to
operate without interruption.
If the operator returns to the seat within
approximately one second, current flow is
re-established to the time delay IC before it has a
chance to “time out” and stop current flow to the
transistor. Current flow is NOT interrupted to the fuel
shutoff solenoid, allowing the engine to continue
operating.
OPERATOR OFF SEAT—MACHINE IN NEUTRAL
AND PTO DISENGAGED:
When operator is off the seat, current to the fuel
shutoff solenoid can still be maintained through the
interlock circuit. For current to flow through the
interlock circuit, the key switch must be turned to the
RUN or START position, the hydrostatic control lever
in the N/STOP position, and PTO switch(es) in the
OFF position (PTO disengaged).
With these conditions met, current flows from fuse
(F1) through the interlock contacts of the PTO
switches, transmission neutral switch, to pin “7” of
TDC module 8-pin connector (X13). Inside the TDC
module, current flows from pin “7” to fuel shut-off
transistor (C). As long as current from the interlock
circuit flows to transistor (C), the transistor is
“switched on”. In this state, the transistor provides an
alternate path to ground for the fuel shut-off relay
coil. The fuel shutoff relay contacts close, allowing
current to flow to the fuel shutoff solenoid.
The 25-amp fuse (F1) and 10-amp fuse (F2) protect
the fuel shutoff circuit from excessive current.
The 8-amp circuit breaker (F5) disables the start
circuit and fuel shutoff solenoid (solenoid will not
energize) if breaker is tripped.
Due to post size limits the three wire version manual text needs to be in my next post....
Chuck
Joined
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10,553 Posts
Now for the three wire theory of operation:
The function of the fuel shutoff solenoid circuit is to
stop engine operation by shutting off fuel flow to the
fuel injector pump. This is accomplished either
manually using the key switch or automatically when
the operator rises from the seat for more than one
second with machine in gear or PTO engaged.
OPERATOR ON SEAT—MACHINE IN GEAR
AND/OR PTO ENGAGED:
When the key switch (S1) is turned to the ON
position, current flows from the positive (+) terminal of
battery (G1), through fusible link (F4) to the key
switch. Current flows across key switch contacts to
25-amp fuse (F1) and 10-amp fuse (F2). From fuse
(F2), current flows across the closed contacts of seat
switch (S6) to pin “A” of TDC module 3-pin connector
(X14).
Inside the TDC module, current flows to seat time
delay IC (J), then to time delay transistor (H). As long
as current from IC (J) flows to transistor (H), the
transistor is “switched on”. In this state, the transistor
completes the path to ground, allowing current from
the seat switch to flow through relay coil (D),
energizing the relay. This closes contacts (C), which
allows current from fuse (F1), to flow to solenoid (Y3)
hold-in windings (B). The magnetic field produced in
the hold-in windings is not strong enough to move the
armature of fuel shutoff solenoid by itself.
From relay contacts (C), current also flows to pull-in
time delay IC (G) and pull-in relay coil (F). IC (G)
provides a path to ground for relay coil (F), causing
the relay to energize and close relay contacts (E).
This allows high current from the battery to flow
through fusible link (F4), across relay contacts (E), to
solenoid pull-in windings (A). This energizes the
pull-in coil, which pulls the fuel shutoff solenoid
armature in and moves the injection pump linkage to
the ON position.
<u>After approximately one second, IC (G) breaks the
pull-in relay’s path to ground, thus stopping current
flow through the relay coil. The relay contacts (E)
open, causing current to stop flowing to the solenoid
pull-in windings.</u>
Current continues to flow to the solenoid hold-in
windings. The magnetic field produced by this current
is strong enough to hold the solenoid armature in,
thus keeping the injector pump linkage at the ON
position.
When the operator rises from the seat, the seat
switch contacts open, causing current to stop flowing
to seat time delay IC (J). If the operator does not
return to the seat within approximately one second,
IC (J) stops current flow to transistor (H). The
transistor will “switch off”, stopping current flowing
through relay coil (D), causing relay contacts (C) to
open. Current stops flowing to the solenoid hold-in
windings, de-energizing the fuel shutoff solenoid. With
the solenoid no longer energized, a return spring
moves the injector pump linkage back to the OFF
position, thus stopping fuel flow to the injection pump.
NOTE: Driving the machine over rough terrain can
cause the seat switch contacts to momentarily
open and close. If this happens, the seat time
delay IC allows the engine to operate without
interruption.
If the operator returns to the seat within
approximately one second, current flow is
re-established to IC (J) before it has a chance to
“time out” and stop current flow to transistor (H).
Current flow is NOT interrupted to the fuel shutoff
solenoid, allowing the engine to continue operating.
OPERATOR OFF SEAT—MACHINE IN NEUTRAL
AND PTO DISENGAGED:
NOTE: 332 (S.N. 596723— ) and 430 (S.N.
596048— ); Park brake must be engaged.
When operator is off the seat, current to the fuel
shutoff solenoid can still be maintained through the
interlock circuit. For current to flow through the
interlock circuit, the key switch must be turned to the
ON or START position, the hydrostatic control lever in
the N/STOP position, the PTO switches in the OFF
position (PTO disengaged) and park brake engaged
(332 (S.N. 596723— ) and 430 (S.N. 596048— )
only).
With these conditions met, current flows from fuse
(F1), through the interlock contacts of the PTO
switches, transmission neutral switch, and brake
switch (if equipped) to pin “A” of TDC module 6-pin
connector (X13). Inside the TDC module, the interlock
current flows to transistor (I), causing the transistor to
“switch on”. In this state, the transistor provides an
alternate path to ground for relay coil (D). The relay
coil energizes, closing relay contacts (C), thus
allowing current to flow to the fuel shutoff solenoid
hold-in windings (B).
...Hope this helps.
Chuck}
The function of the fuel shutoff solenoid circuit is to
stop engine operation by shutting off fuel flow to the
fuel injector pump. This is accomplished either
manually using the key switch or automatically when
the operator rises from the seat for more than one
second with machine in gear or PTO engaged.
OPERATOR ON SEAT—MACHINE IN GEAR
AND/OR PTO ENGAGED:
When the key switch (S1) is turned to the ON
position, current flows from the positive (+) terminal of
battery (G1), through fusible link (F4) to the key
switch. Current flows across key switch contacts to
25-amp fuse (F1) and 10-amp fuse (F2). From fuse
(F2), current flows across the closed contacts of seat
switch (S6) to pin “A” of TDC module 3-pin connector
(X14).
Inside the TDC module, current flows to seat time
delay IC (J), then to time delay transistor (H). As long
as current from IC (J) flows to transistor (H), the
transistor is “switched on”. In this state, the transistor
completes the path to ground, allowing current from
the seat switch to flow through relay coil (D),
energizing the relay. This closes contacts (C), which
allows current from fuse (F1), to flow to solenoid (Y3)
hold-in windings (B). The magnetic field produced in
the hold-in windings is not strong enough to move the
armature of fuel shutoff solenoid by itself.
From relay contacts (C), current also flows to pull-in
time delay IC (G) and pull-in relay coil (F). IC (G)
provides a path to ground for relay coil (F), causing
the relay to energize and close relay contacts (E).
This allows high current from the battery to flow
through fusible link (F4), across relay contacts (E), to
solenoid pull-in windings (A). This energizes the
pull-in coil, which pulls the fuel shutoff solenoid
armature in and moves the injection pump linkage to
the ON position.
<u>After approximately one second, IC (G) breaks the
pull-in relay’s path to ground, thus stopping current
flow through the relay coil. The relay contacts (E)
open, causing current to stop flowing to the solenoid
pull-in windings.</u>
Current continues to flow to the solenoid hold-in
windings. The magnetic field produced by this current
is strong enough to hold the solenoid armature in,
thus keeping the injector pump linkage at the ON
position.
When the operator rises from the seat, the seat
switch contacts open, causing current to stop flowing
to seat time delay IC (J). If the operator does not
return to the seat within approximately one second,
IC (J) stops current flow to transistor (H). The
transistor will “switch off”, stopping current flowing
through relay coil (D), causing relay contacts (C) to
open. Current stops flowing to the solenoid hold-in
windings, de-energizing the fuel shutoff solenoid. With
the solenoid no longer energized, a return spring
moves the injector pump linkage back to the OFF
position, thus stopping fuel flow to the injection pump.
NOTE: Driving the machine over rough terrain can
cause the seat switch contacts to momentarily
open and close. If this happens, the seat time
delay IC allows the engine to operate without
interruption.
If the operator returns to the seat within
approximately one second, current flow is
re-established to IC (J) before it has a chance to
“time out” and stop current flow to transistor (H).
Current flow is NOT interrupted to the fuel shutoff
solenoid, allowing the engine to continue operating.
OPERATOR OFF SEAT—MACHINE IN NEUTRAL
AND PTO DISENGAGED:
NOTE: 332 (S.N. 596723— ) and 430 (S.N.
596048— ); Park brake must be engaged.
When operator is off the seat, current to the fuel
shutoff solenoid can still be maintained through the
interlock circuit. For current to flow through the
interlock circuit, the key switch must be turned to the
ON or START position, the hydrostatic control lever in
the N/STOP position, the PTO switches in the OFF
position (PTO disengaged) and park brake engaged
(332 (S.N. 596723— ) and 430 (S.N. 596048— )
only).
With these conditions met, current flows from fuse
(F1), through the interlock contacts of the PTO
switches, transmission neutral switch, and brake
switch (if equipped) to pin “A” of TDC module 6-pin
connector (X13). Inside the TDC module, the interlock
current flows to transistor (I), causing the transistor to
“switch on”. In this state, the transistor provides an
alternate path to ground for relay coil (D). The relay
coil energizes, closing relay contacts (C), thus
allowing current to flow to the fuel shutoff solenoid
hold-in windings (B).
...Hope this helps.
Chuck}
Joined
·
10,553 Posts
Fred,
The delay shutoff on later garden tractors and lawn tractors like my Deere x304 is indeed meant to burn some gas out or the carburetor *after* the fuel shutoff solenoid is closed so no new fuel enters the float chamber. Not so much a safety item as a way to ensure that an air cooled engine does not heat the cool air in the float chamber enough to expand it and cause the engine to flood so much that it cannot be started in the half hour after it is shut down.
That shut off delay used in later machines is NOT the same as the TDCM that is mentioned in the threads about the 316 Onan, 318, 322, 332, 420 and 430 tractors. Yes that group is a mix of both gas and diesel powered open frame units...
The TDCM function in vintage open frame garden tractors is to delay the shutoff of the engine when the operator leaves the seat for more than a half second or so. The delay is to avoid false triggering of the safety shutdown over rough terrain and bouncing in the seat is common. All of this is well explained in the theory of operation section in the TM1590 and 1591 service manuals. As the only 'smarts' in these tractors the TDCM also contains the voltage sensing circuits that drive the charge indicator lamp on the dash. Here is a typical wiring excerpt showing the fuel shutoff function of the TDCM for the diesel 322:
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...And here is the similar function that kills the ignition in the gas powered 322 tractor:
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Notice that in the case of the gas 322, the fuel shutoff and the ignition are killed at the same time by the removal of voltage at pin 2 of the TDCM -- so burning off fuel is not a feature here. Further, there is no fuel shutoff valve/solenoid at all on the Onan powered gas engined 316, 318 or 420...
Chuck
The delay shutoff on later garden tractors and lawn tractors like my Deere x304 is indeed meant to burn some gas out or the carburetor *after* the fuel shutoff solenoid is closed so no new fuel enters the float chamber. Not so much a safety item as a way to ensure that an air cooled engine does not heat the cool air in the float chamber enough to expand it and cause the engine to flood so much that it cannot be started in the half hour after it is shut down.
That shut off delay used in later machines is NOT the same as the TDCM that is mentioned in the threads about the 316 Onan, 318, 322, 332, 420 and 430 tractors. Yes that group is a mix of both gas and diesel powered open frame units...
The TDCM function in vintage open frame garden tractors is to delay the shutoff of the engine when the operator leaves the seat for more than a half second or so. The delay is to avoid false triggering of the safety shutdown over rough terrain and bouncing in the seat is common. All of this is well explained in the theory of operation section in the TM1590 and 1591 service manuals. As the only 'smarts' in these tractors the TDCM also contains the voltage sensing circuits that drive the charge indicator lamp on the dash. Here is a typical wiring excerpt showing the fuel shutoff function of the TDCM for the diesel 322:
...And here is the similar function that kills the ignition in the gas powered 322 tractor:
Notice that in the case of the gas 322, the fuel shutoff and the ignition are killed at the same time by the removal of voltage at pin 2 of the TDCM -- so burning off fuel is not a feature here. Further, there is no fuel shutoff valve/solenoid at all on the Onan powered gas engined 316, 318 or 420...
Chuck
Joined
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10,553 Posts
You can use an ohm meter to measure the resistance of each of the fuel solenoid's windings, but from what you have observed the pull-in coil (white wire connection...) may be burned out. The other possibility is that the voltage pulse out of the TDCM on pin x13 E is not present for the one second following the key first being turned to RUN, but that is much less likely...
Let us know what you find, of course.
Chuck
Let us know what you find, of course.
Chuck
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