OEM Ignition Switch for ZD326 Worth the Extra $70+?
- Thread starter Mr Haney
- Start date
Russell King
Well-known member
Lifetime Member
Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Back to the safety switch logic for a moment. On my Cub Cadet you can’t get off the seat with it running UNLESS the parking brake is set. I think if the blades are on you then you just CAN’T get off the seat and keep the engine running. That is why they have a switch on the brake pedal.
I assume that is also similar on your mower, but can you confirm that?
I assume that is also similar on your mower, but can you confirm that?
That's right. You basically have to power the solenoid (for 8 seconds in my tractor) when power has just been removed through the starter switch. Power can be held with a field effect transistor easily. I just wanted to point that out when you use an off the shelf timer.
A simple momentary kill switch would work fine if you do not mind the extra action required. That is the trouble with Diesel engines with mechanical injection pumps. They are difficult to stop once they run
All this praise for safety switches and kudus on Kubota for using several on their machines remind me of a thread down the list here called "Brake problem" where the dealer thinks no brakes in one direction meets Kubota's ridged standards.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
simply install a form B (normally closed) fuel valve in the fuel line. No power to it, NO fuel to Injpump, engine stops running.That's right. You basically have to power the solenoid (for 8 seconds in my tractor) when power has just been removed through the starter switch. Power can be held with a field effect transistor easily. I just wanted to point that out when you use an off the shelf timer.
A simple momentary kill switch would work fine if you do not mind the extra action required. That is the trouble with Diesel engines with mechanical injection pumps. They are difficult to stop once they run
Good luck finding a NE555 timer. Do they still make them? I used them in electronic designs 40 years ago
I jumped the relay, and the mower runs like a dream. Well, it did on the right tank. Looks like the left tank has some diesel cheese in it somewhere. Maybe the original owner treated it like a one-tank mower and rarely emptied the left tank.
I made a jumper for the relay and then wrapped it in electrical tape.
Someone recommended Clear-Diesel, so I put some in each tank. Maybe the left tank will clear up. I don't look forward to draining 5 gallons of diesel and finding a home for it.
The fuel filters are just fine. If they weren't, the mower wouldn't run well on either tank. I may change them anyway once I get the electrical problems fixed for good.
The mower looks nasty in the photo. It was a lot cleaner before it met this dusty yard.
As for 555 timers, I have some somewhere.
I think I've found the ECM ground, but I didn't feel like wrestling with it today.
There is no good reason to touch the starter system until daytime temperatures go below 75, so apart from putting in the new relays I ordered, I will try to leave it alone.
I made a jumper for the relay and then wrapped it in electrical tape.
Someone recommended Clear-Diesel, so I put some in each tank. Maybe the left tank will clear up. I don't look forward to draining 5 gallons of diesel and finding a home for it.
The fuel filters are just fine. If they weren't, the mower wouldn't run well on either tank. I may change them anyway once I get the electrical problems fixed for good.
The mower looks nasty in the photo. It was a lot cleaner before it met this dusty yard.
As for 555 timers, I have some somewhere.
I think I've found the ECM ground, but I didn't feel like wrestling with it today.
There is no good reason to touch the starter system until daytime temperatures go below 75, so apart from putting in the new relays I ordered, I will try to leave it alone.
I am pasting what I wrote for my own reference. Seems correct, but then you get what you pay for, so beware.
KUBOTA ZD326 STARTING CIRCUITRY
Some of this material is repetitious because it makes it easier to understand. Wire color codes follow at the end.
OVERVIEW
The starting system's main parts of interest are the ignition switch, ECM (controller), starter relay, starter (includes solenoid), two NO motion lever safety switches, one NO seat safety switch, one NO PTO lever safety switch, and one NC brake safety switch.
N=normally. O=open. C=closed. "Normal" means the mower will not start.
PURPOSE OF ECM
The ECM's only purposes are 1) to monitor the safety switches and either agree or refuse to tell the starter relay to start, and 2) to power the relay that shuts down the mower. When the key is turned to the stop position, the ECM closes the shut-off relay for about 10 seconds, cutting off fuel.
It does not do anything essential, like making the engine run correctly. It can be bypassed completely if necessary. The ECM is not likely to fail, but if everything else has been checked, and the symptoms are consistent with ECM failure, it has to be replaced. It can't be repaired without extraordinary effort.
A failed ECM can cause the mower to refuse to crank or stop. A failed shut-off solenoid can prevent the mower from starting and stopping, but it can't prevent it from cranking.
A bad ground or other connection can simulate ECM failure.
The ECM has 9 connections.
OR = positive from PTO switch
BR = positive to starter relay coil
GB = positive from left motion control lever switch
WL = power to shut-off solenoid.
B = ground
YR = positive from seat switch
RY = positive from ignition switch terminal AC
WB = positive from brake switch
RW = positive to shut-off relay coil
RELATIONSHIP OF IGNITION SWITCH TO ECM
The ignition switch has a rotating conductor (terminal B) which is turned by the key and always hot. It is always connected to the R positive wire. When turned to any position other than off (glow plug, start), it is in contact with terminal AC, which can be considered the ignition's ECM terminal.
Terminal AC is connected to the ECM (controller) and all safety switches (motion lever, seat, PTO, brake). The motion lever switches are in series, so 13 (right) is connected to RY and AC, and 14 (left) is connected to the ECM, providing positive input. The path goes AC-RY-left switch-right switch-ECM.
NORMAL START PROCEDURE
To start, close every switch except the brake switch (levers at rest, PTO off, operator in seat), and open the brake switch by applying the brake. Turn the key partially, letting the glow plug heat if needed. Then turn to the start position and hold until the engine starts.
BYPASSING SWITCHES
The brake safety switch is normally closed (NC). All others are NO. Because it's NC, the brake switch can be bypassed by pulling the connector and covering it. To bypass the other switches, you have to jump them.
HOW IGNITION SWITCH WORKS IN GLOW PLUG POSITION
When the ignition switch is turned partially, it first connects hot terminal B to both terminal AC and terminal 19. Terminal AC feeds the ECM via the RY wire, and terminal 19 runs the glow plug lamp and glow plug.
Terminal 19 is not significant for starting, running, or stopping the mower. Current goes through terminal 19, the lamp and plug, and then to ground. The mower should start and run fine when 19 is out of commission unless the glow plug is needed.
IMPORTANCE OF TERMINAL AC AND RY WIRE TO STARTING
The RY wire that goes from terminal AC to the ECM sends signal through all safety switches along the way. The safety switches all get positive from RY.
IF TERMINAL AC IS BAD OR WIRE RY ISN'T LIVE, THE MOWER WILL NOT START BECAUSE IT WILL ASSUME A MOTION LEVER SWITCH OR THE PTO SWITCH IS IN THE WRONG POSITION.
THE ECM HAS A SINGLE GROUND, AND IF IT FAILS, THE ECM WILL NOT WORK, CAUSING STARTING AND STOPPING PROBLEMS.
HOW IGNITION SWITCH WORKS IN START POSITION
When the ignition switch is turned past the glow plug position, it disconnects 19 and connects hot B to AC and terminal 50 (BY). Terminal 50 feeds voltage through the BY wire to the starter relay. If the relay is closed, the voltage goes out through the BW wire to the starter solenoid. This is the voltage that tells the starter solenoid to turn.
The starter relay is closed by the ECM (not the ignition switch) through the BR wire. The current exits through the relay coil to the B wire (ground). Don't confuse the B (black) wire with the ignition switch B terminal.
To start the mower, the ECM needs to see safety switch positive at YR (seat), OR (PTO), and GB (left motion lever in series with right). It needs to see RY positive next to the brake switch WB input. If it sees positive at the input from the brake switch (WB), the mower will not start. WB should be neither positive nor negative when the mower starts. No input.
STARTER RELAY
The starter relay is #6 in the manual's diagram. It connects to BR (ECM), BY (ignition positive, terminal 50), BW (positive signal to starter), and B (ground) wires. It has 5 connections, one of which is not used. It switches between two poles; off (87A, dead) and on (87, BW). In the rest state, the switch connects the dead pole. Terminal 87 is the BW wire which goes to the starter solenoid.
Terminals 85 (BR) and 86 (B) send ECM juice through the coil. They are connected to the BR (ECM hot output) and B (ground) wires. The B wire is not important for analysis, since it never changes. A positive input has to be connected to BR in order for the relay to close, and the ECM does this. BR exits the ECM next to OR, if the schematic is any indication.
When the relay closes, it connects the relay switch's BY wire (positive input from terminal 50) to the BW wire that feed the starter solenoid. This starts the mower.
On the schematic, from top to bottom, the starter relay connections are:
1. ECM - BR
2. Ignition switch - BY
3. Starter - BW
4. Ground - B
Jumping BY and BW should bypass the ECM and start the mower without harming anything. UPDATE: I tested this, and it works just fine.
The shut-off solenoid can also be set up this way, but you have to put in a timer or a momentary switch, because if the solenoid is always trying to shut off when the key is in the stop position, the battery will drain.
The manual shut-off lever is easily reached at the right rear of the mower.
TESTING RELAYS
All three relays on the mower are the same. You can test resistances to see if they are working. The manual's test resistances are wrong.
Resistances: 85-86: ~90 ohms (coil)
87-87A: infinite
87-30: infinite
30-87A: 0 ohms
REMOVING IGNITION SWITCH
Use a pin spanner to turn the outer switch cover to unscrew it. Remove the cover over the motion lever arm switch. Remove all screws from the control panel so it is loose. Push the ignition switch down under the panel, pull it out between the panel and fender, depress the tab on the connector, and remove the switch.
DISASSEMBLING IGNITION SWITCH
There are two tabs on the sides of the switch housing. Pull them outward while pushing up on the key cylinder (keyhole). It helps to put a small object in a vise and rest the key cylinder on it while you pull the tabs and push the switch down.
By comparing the ignition wire colors to the switch's terminals, you can figure out which terminal does what and how to check resistances to see if the switch is good. Removing oxidation from the copper contacts can reduce excess resistance.
WIRE COLOR CODES
B black
BR black/red
BW black/white
BY black/yellow
G green
GB green/black
L blue
LW blue/white
OR orange
ORL orange/black
P pink
R red
RB red/black
RG red/green
RL red/blue
RW red/white
RY red/yellow
V violet
W white
WB white/black
WG white/green
WL white/blue
Y yellow
YL yellow/blue
YR yellow/red
YW yellow/white
KUBOTA ZD326 STARTING CIRCUITRY
Some of this material is repetitious because it makes it easier to understand. Wire color codes follow at the end.
OVERVIEW
The starting system's main parts of interest are the ignition switch, ECM (controller), starter relay, starter (includes solenoid), two NO motion lever safety switches, one NO seat safety switch, one NO PTO lever safety switch, and one NC brake safety switch.
N=normally. O=open. C=closed. "Normal" means the mower will not start.
PURPOSE OF ECM
The ECM's only purposes are 1) to monitor the safety switches and either agree or refuse to tell the starter relay to start, and 2) to power the relay that shuts down the mower. When the key is turned to the stop position, the ECM closes the shut-off relay for about 10 seconds, cutting off fuel.
It does not do anything essential, like making the engine run correctly. It can be bypassed completely if necessary. The ECM is not likely to fail, but if everything else has been checked, and the symptoms are consistent with ECM failure, it has to be replaced. It can't be repaired without extraordinary effort.
A failed ECM can cause the mower to refuse to crank or stop. A failed shut-off solenoid can prevent the mower from starting and stopping, but it can't prevent it from cranking.
A bad ground or other connection can simulate ECM failure.
The ECM has 9 connections.
OR = positive from PTO switch
BR = positive to starter relay coil
GB = positive from left motion control lever switch
WL = power to shut-off solenoid.
B = ground
YR = positive from seat switch
RY = positive from ignition switch terminal AC
WB = positive from brake switch
RW = positive to shut-off relay coil
RELATIONSHIP OF IGNITION SWITCH TO ECM
The ignition switch has a rotating conductor (terminal B) which is turned by the key and always hot. It is always connected to the R positive wire. When turned to any position other than off (glow plug, start), it is in contact with terminal AC, which can be considered the ignition's ECM terminal.
Terminal AC is connected to the ECM (controller) and all safety switches (motion lever, seat, PTO, brake). The motion lever switches are in series, so 13 (right) is connected to RY and AC, and 14 (left) is connected to the ECM, providing positive input. The path goes AC-RY-left switch-right switch-ECM.
NORMAL START PROCEDURE
To start, close every switch except the brake switch (levers at rest, PTO off, operator in seat), and open the brake switch by applying the brake. Turn the key partially, letting the glow plug heat if needed. Then turn to the start position and hold until the engine starts.
BYPASSING SWITCHES
The brake safety switch is normally closed (NC). All others are NO. Because it's NC, the brake switch can be bypassed by pulling the connector and covering it. To bypass the other switches, you have to jump them.
HOW IGNITION SWITCH WORKS IN GLOW PLUG POSITION
When the ignition switch is turned partially, it first connects hot terminal B to both terminal AC and terminal 19. Terminal AC feeds the ECM via the RY wire, and terminal 19 runs the glow plug lamp and glow plug.
Terminal 19 is not significant for starting, running, or stopping the mower. Current goes through terminal 19, the lamp and plug, and then to ground. The mower should start and run fine when 19 is out of commission unless the glow plug is needed.
IMPORTANCE OF TERMINAL AC AND RY WIRE TO STARTING
The RY wire that goes from terminal AC to the ECM sends signal through all safety switches along the way. The safety switches all get positive from RY.
IF TERMINAL AC IS BAD OR WIRE RY ISN'T LIVE, THE MOWER WILL NOT START BECAUSE IT WILL ASSUME A MOTION LEVER SWITCH OR THE PTO SWITCH IS IN THE WRONG POSITION.
THE ECM HAS A SINGLE GROUND, AND IF IT FAILS, THE ECM WILL NOT WORK, CAUSING STARTING AND STOPPING PROBLEMS.
HOW IGNITION SWITCH WORKS IN START POSITION
When the ignition switch is turned past the glow plug position, it disconnects 19 and connects hot B to AC and terminal 50 (BY). Terminal 50 feeds voltage through the BY wire to the starter relay. If the relay is closed, the voltage goes out through the BW wire to the starter solenoid. This is the voltage that tells the starter solenoid to turn.
The starter relay is closed by the ECM (not the ignition switch) through the BR wire. The current exits through the relay coil to the B wire (ground). Don't confuse the B (black) wire with the ignition switch B terminal.
To start the mower, the ECM needs to see safety switch positive at YR (seat), OR (PTO), and GB (left motion lever in series with right). It needs to see RY positive next to the brake switch WB input. If it sees positive at the input from the brake switch (WB), the mower will not start. WB should be neither positive nor negative when the mower starts. No input.
STARTER RELAY
The starter relay is #6 in the manual's diagram. It connects to BR (ECM), BY (ignition positive, terminal 50), BW (positive signal to starter), and B (ground) wires. It has 5 connections, one of which is not used. It switches between two poles; off (87A, dead) and on (87, BW). In the rest state, the switch connects the dead pole. Terminal 87 is the BW wire which goes to the starter solenoid.
Terminals 85 (BR) and 86 (B) send ECM juice through the coil. They are connected to the BR (ECM hot output) and B (ground) wires. The B wire is not important for analysis, since it never changes. A positive input has to be connected to BR in order for the relay to close, and the ECM does this. BR exits the ECM next to OR, if the schematic is any indication.
When the relay closes, it connects the relay switch's BY wire (positive input from terminal 50) to the BW wire that feed the starter solenoid. This starts the mower.
On the schematic, from top to bottom, the starter relay connections are:
1. ECM - BR
2. Ignition switch - BY
3. Starter - BW
4. Ground - B
Jumping BY and BW should bypass the ECM and start the mower without harming anything. UPDATE: I tested this, and it works just fine.
The shut-off solenoid can also be set up this way, but you have to put in a timer or a momentary switch, because if the solenoid is always trying to shut off when the key is in the stop position, the battery will drain.
The manual shut-off lever is easily reached at the right rear of the mower.
TESTING RELAYS
All three relays on the mower are the same. You can test resistances to see if they are working. The manual's test resistances are wrong.
Resistances: 85-86: ~90 ohms (coil)
87-87A: infinite
87-30: infinite
30-87A: 0 ohms
REMOVING IGNITION SWITCH
Use a pin spanner to turn the outer switch cover to unscrew it. Remove the cover over the motion lever arm switch. Remove all screws from the control panel so it is loose. Push the ignition switch down under the panel, pull it out between the panel and fender, depress the tab on the connector, and remove the switch.
DISASSEMBLING IGNITION SWITCH
There are two tabs on the sides of the switch housing. Pull them outward while pushing up on the key cylinder (keyhole). It helps to put a small object in a vise and rest the key cylinder on it while you pull the tabs and push the switch down.
By comparing the ignition wire colors to the switch's terminals, you can figure out which terminal does what and how to check resistances to see if the switch is good. Removing oxidation from the copper contacts can reduce excess resistance.
WIRE COLOR CODES
B black
BR black/red
BW black/white
BY black/yellow
G green
GB green/black
L blue
LW blue/white
OR orange
ORL orange/black
P pink
R red
RB red/black
RG red/green
RL red/blue
RW red/white
RY red/yellow
V violet
W white
WB white/black
WG white/green
WL white/blue
Y yellow
YL yellow/blue
YR yellow/red
YW yellow/white
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
this .... ORL orange/black should probably be ORB orang/black , to be consistent with B being black....
Wrt to the NC brake switch... is that really open when the brake is applied? I believe the NC refers to the switch lying open outside the tractor. For a safety function I would imagine the switch closed being safe (brake applied). So is it possible that it is mounted mechanically to be open when brake is open?
Yes, I know it's a different part. What I meant was that I cannot believe that it is open when brake applied. I think it is closed when brake applied.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
I've got 2 or 3 'tubes' of them here, industrial temp range.... still made, though cheaper to buy a PIC microcontroller !Good luck finding a NE555 timer. Do they still make them? I used them in electronic designs 40 years ago
The schematic shows the switches in the normal position, and only the brake switch is closed.
When I described the purpose of the controller, I completely forgot the third function. It runs the horn that goes off when the mower overheats. The mower has a perfectly good temperature gauge on the control panel, though.
Interesting thing: my L3710 is a more complex machine than the ZD326. It has HST, 4-wheel-drive, two PTO's, and more hydraulics, but it runs fine with no ECM.
Interesting thing: my L3710 is a more complex machine than the ZD326. It has HST, 4-wheel-drive, two PTO's, and more hydraulics, but it runs fine with no ECM.