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Need a guru Kohler 26hp EFI **FIXED**

#1

J

jjreds01

Laser Z SN 332739
Bought this used and only got a couple hrs on it.
Mower ran but wouldn't charge battery.
Tested the stator it was shorted.
Pulled motor found flywheel magnets were loose.
Epoxied magnets back on flywheel +-+-+- etc
Replaced stator.
Key on, fuel pump runs, solenoid clicks no start.
Jumped switch start to trigger wire on starter. Starter works, no power to coils.
Diagnostic only shows 61.
Coils do power up for the 1-2 secs when the fuel pump runs.
Control levers switch ignition on and off as expected.
Brake switch is working per the wiring diagram and does switch ignition on when closed.
24 pin plastic ECU case.
Pin 1, 2, 15 ok. As expected.
Pin 3 and 10 are open. I didn't expect that.
I don't know if I've got 1 or 2 problems could really use some troubleshooting assistance to get the ignition working, thank you


#2

I

ILENGINE

I am leaning toward the ECU not seeing input from the speed sensor. And if it can't see the engine rotating it won't fire the coils for spark.


#3

J

jjreds01

ILENGINE said:
I am leaning toward the ECU not seeing input from the speed sensor. And if it can't see the engine rotating it won't fire the coils for spark.
Click to expand...
Thank you. Is there a test I can do to check it? There is no power to the coils. Pin 3 safety is open is that permission to start? And pin 10 speed sensor ground - should I see a ground there with ECU unplugged?


#4

I

ILENGINE

https://resources.kohler.com/power/kohler/enginesUS/pdf/24_690_01_EN.pdf page 119 should be your speed sensor test.


#5

J

jjreds01

Thanks I'll check the resistance between pin 9 and 10 on the ECU in the morning and report back


#6

J

jjreds01

ILENGINE said:
https://resources.kohler.com/power/kohler/enginesUS/pdf/24_690_01_EN.pdf page 119 should be your speed sensor test.
Click to expand...
928 ohms @ ECU pin 9 & 10
928 ohms @ 3 pin sensor connector
Relay mounted to chassis clicks when turning key to start position. No starter signal, no juice to coils.
Starter is ok - works by energizing signal wire.


#7

I

ILENGINE

Sounds like a safety switch is not working correctly. Park brake or direction control arms not activating safety switches for start


#8

J

jjreds01

ILENGINE said:
Sounds like a safety switch is not working correctly. Park brake or direction control arms not activating safety switches for start
Click to expand...


#9

J

jjreds01

That was the first thing I checked. As stated in my OP. All three switches are working. In the run position I've got power to the start relay, fuel pump relay, pin 2 on the ECU switched power. No power to coils. Fuel pump runs on key on for 1-2 sec.


#10

I

ILENGINE

jjreds01 said:
That was the first thing I checked. As stated in my OP. All three switches are working. In the run position I've got power to the start relay, fuel pump relay, pin 2 on the ECU switched power. No power to coils. Fuel pump runs on key on for 1-2 sec.
Click to expand...
fuel pump, coils and injectors all get their power from the same pin of the start relay. the ECU shuts that system off after 2 seconds to prevent the fuel pump from running constantly if the engine is not running. And turns it back on with engine crank. I don't see anything on the engine side of the system that would prevent the engine from cranking. So I would be concentrating on what is preventing power to the starter solenoid in the crank position. Something is not working properly between the key switch in the start position and the starter solenoid on the engine. Did you also check the PTO switch. Whatever is preventing cranking is likely also effecting pin 3.

What happens if you ground pin 3 and then jump the solenoid to crank the engine. Pin three may be ground to run.


#11

J

jjreds01

Yes PTO works with the key switch in the on position. I'll have to see if I can open up the ECU connector to figure out which wire feeds pin 3. The start relay just clicks. I can put a jumper across it and the starter will work with the key switch so switch to relay is good, relay to solenoid is good, but still no pixies at the coils. I've changed the relay with a known good one, no joy. The other two start relay terminals have +, - as expected. All I did when pulling the engine was disconnect the ECU and 5 pin motor plug, main ground and voltage regulator ground. I'm baffled. I'll chase pin 3 and the grounds. thanks


#12

J

jjreds01

ILENGINE said:
fuel pump, coils and injectors all get their power from the same pin of the start relay. the ECU shuts that system off after 2 seconds to prevent the fuel pump from running constantly if the engine is not running. And turns it back on with engine crank. I don't see anything on the engine side of the system that would prevent the engine from cranking. So I would be concentrating on what is preventing power to the starter solenoid in the crank position. Something is not working properly between the key switch in the start position and the starter solenoid on the engine. Did you also check the PTO switch. Whatever is preventing cranking is likely also effecting pin 3.

What happens if you ground pin 3 and then jump the solenoid to crank the engine. Pin three may be ground to run.
Click to expand...
My mower has a separate fuel pump relay and I couldn't find a wiring diagram that shows 2 relays. Before I start grounding ECU pins I'd like to understand how those circuits affect the start circuit. Your comment about pump coils and start on the same pin got me thinking thanks


#13

I

ILENGINE

Wiring diagrams for mowers can be complicated because you have the wiring diagram for the mower and the wiring diagram for the engine. And those two diagrams have to mate together. So the question comes down to is the start relay part of the mower wiring or the engine wiring. And the pin 3 safety wire on the ECU may mate with components on the mower wiring diagram which could effect spark, causing the no start. I think the no crank without jumping the solenoid and the no start when cranking are separate issues, but one may effect the other.

I would start with the no crank issue and chase the battery voltage from the battery to the key switch through the S terminal of the switch to what ever components it goes though to the start relay. If found out were you are loosing power. And if you have input into the start relay but nothing out then start backtracking the trigger side of the relay to see what makes it work and what needs to be in place to make it work. You will need both the engine diagram and the mower diagram to chase it down.

I have come across cases where the wiring diagrams cover 15-20 pages. I have even enlarged diagrams and then printed them out over several pages and spread them out and tape them together just to follow the path.


#14

J

jjreds01

Found it. Stupid mistake. Had "I" plugged into "A" on the key switch.
Thanks for hanging in there.


#15

I

ILENGINE

jjreds01 said:
Found it. Stupid mistake. Had "I" plugged into "A" on the key switch.
Thanks for hanging in there.
Click to expand...
Good to know. Sometimes things can get overwhelming when you are presented with multiple things at once. I have learned over the years that if you have multiple problems on the same piece of equipment chase 1 thing at a time.


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