exmark lazar z electrical problem

jackcu

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Hello all. I am working on Exmark mower for a friend of mine. This machine sat for a couple of months without running then it went through hurricane Harvey and was flooded in 4 feet of water. It was running when parked. I have flushed the engine but now have an electrical problem. It will not turn over. Battery and cables are good. I think the problem is in one of the safety switches, or maybe on the kill circuit. I can not get it to turn over when turning the key. I have replaced both start and kill circuit relays.
I can hear the starter circuit relay and the kill circuit replays clicking when i turn the key so I know its getting power to the relays, but its not turning over. When I apply a jumper wire from the (red) hot wire from the ignition switch to the orange and black wire at the start relay I can get the engine to turn over, but there is no spark unless i unplug the kill circuit. Basically I am bypassing the start relay to at least get it to turn over but apparently the kill circuit is still in operation when I bypass the start relay. If I turn on the PTO while the start relay is bypassed then the blades turn when trying to start the engine. I have checked continuity at all the switches which are good. I have checked continuity of all wires on each circuit and found no broken wires at all. I can not think of any thing else to check. Questions to follow.

1. How many safety switches are there on this machine? I count 4, one on each control arm, one on there parking brake, and one the seat. Are there more? Is the PTO wired into the kill circuit?

2. With the start replay bypassed why is it turning over but no spark?

Model number is LPH19KA465, serial number is 741097

I added an electrical schematic

Any help at all would be appreciated. My email is [email protected] Thanks for reading.
 

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bertsmobile1

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There are 2 safety circuits active when starting.
One controls the + feed to the starter solenoid
The other is a kill circuit to the magneto which is a ground circuit.
Some of the switches are double pole so are in both circuits .
Cranking circuit will be the PTO switch & Parking Brake switch. On some ZTR's the seat switch as well.
The kill circuit is the lap bars & parking brake.

Exmark further complicate it by adding the relays and from memory all wires are ground wires and the relays use the ground side to do the triggering.
This is a good idea because it limits the chance of a short circuit to ground but it does make servicing harder.

Do you have the circuit diagram for your mower ?
We do not get Exmark down here so I have no servicing information on them.

However you might like to pull the relays and check for continuity between the ground terminal and ground.
It should make & break as you change the various controls.
Using ground to control things throws a lot of people who always thing about switching power not ground.
 

jackcu

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I do have the electrical schematic to this machine. I will try and work on the circuits you told me about. Thanks so much for the help.
 

bertsmobile1

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If you can scan, get a clear photo or post the URL for the circuit diagram you will get a lot more help.
There are a lot of people here who read circuit diagrams like sheet music and while not being familiar with your mower will be able to tell you what to check and how to check it.
 

jackcu

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Here is the electrical schematic for this machine
 

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jackcu

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It was a relay that I bought that was NIB but when I tested it the relay was bad. When I took it back we tested it at the store and confirmed it was bad. So moral of that story is check electrical components, even if its NIB.
 

StaffordNurseries

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Thank you for this handy post. I used it as a guide to get my laser z started. Was able to check the function of every switch. Not really sure which one I unplugged and plugged back in that got the spark back, but it was running within 2 hrs from reading this.
 
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