92 Marathon

79camaro · 11-04-2012, 03:58 PM

I've been trying to bring a 92 marathon that's been sitting for a few years back to life. These forums have been a lifesaver! I've found most of the troubleshooting from searching, but now I am at a stopping point. I've put in new batteries, replaces the solenoid, and have confirmed the motor works by wiring it directly to a spare battery. It seems I have all the voltage in all the right places, but I am unsure how to check to see if the controller is shot? The other thing I am unclear about is the controller side of the solenoid (the two large opposing posts that is) is reading 13 volts, the battery side is reading 19 volts. I did change out the resistor too. Any ideas? Time to try a new controller?

Taykol · 11-04-2012, 06:19 PM

You should have full battery voltage on the battery side. If 19 is full battery voltage, then charge those new batteries to full, around 38.3 volts. Give some readings of battery voltage and the other tests.

79camaro · 11-04-2012, 07:44 PM

my bad. I was using the voltage from the battery next to the solenoid as the reference voltage. I get 37.2 v on the battery side, and 32 v on the controller side. Thanks in advance!

JohnnieB · 11-05-2012, 06:37 AM

At 37.2V your new batteries are less than 75% charged.
That is high enough for troubleshooting, but the plates are sulfating as we speak, so it would be a good idea to fully charge them.

Is the solenoid clicking?
If so, connect DVM between B- and M- terminals on controller.
Press pedal until solenoid first clicks.
You should read full battery pack voltage.

If not, there is something wrong in High Current loop, which is traced out on attached schematic.

If so, press pedal slowly to floor.
Voltage should decrease smoothly to zero, or close to zero.

If not, either the throttle input to the controller is bad, or the controller is bad.

If so, the cart ought to be running over something, if you didn't jack the rear end off the ground.

79camaro · 11-05-2012, 11:11 PM

Thanks Johnnie! I am only getting 35 volts when the solenoid clicks, and definitely not a smooth transition from 35-0! Thanks for the wiring diagram, I am going to check out the high current loop tomorrow and report back

JohnnieB · 11-06-2012, 05:39 AM

Sounds like three problems.

1. Not getting full battery pack voltage between B- & M- when solenoid first clicks.
That means there is some resistance somewhere in high current loop.
You said the solenoid is new, so it is probably good.
That leaves the F/R switch contacts, all the cables high current cables and connections.

2. Not going smoothly from full pack voltage to zero.
That is probably a dirty wiper on the throttle potentiometer.
Pull the black and white wires off the small terminals and measure between the wires with an ohmmeter.
Should smoothly go from about zero to about 5,000 Ohms.
Some spray cleaner and working it back and forth a few time might clean it up a bit.
Otherwise, it will have to be replaced.

3. Motor not spinning or trying to spin when voltage between B- & M- when from 35V down to zero.
(You didn't mention whether it did or not, so I'm just guessing it didn't.)

You did say that the motor will spin when voltage was applied directly to it, so the cause of this problem is likely the same as #1 above.

Basically, the motor runs, so it is okay and the controller is doing what it is being told to do, but erratically, probably due to an erratic throttle input.

When you find and fix the high resistance in the high current loop, the cart will probably run, but be a bit erratic due the throttle pot issues.

79camaro · 11-06-2012, 07:35 PM

Ok ready to dive in here. When i tool apart the FNR switch (FNR double switch) I notice a connection was missing. I've highlighted the schematic in green. My cart doesn't have a horn so I guess just bypass that bit, but it does look like there is a diode (or fuse) or something on the drawing? Wanted to 2x check before I shorted something.

79camaro · 11-06-2012, 09:20 PM

Johnnie! Your the man. That wire from the FNR switch was it. I replace the missing wire and just got back from a cruise around my street! The fwd reverse is pretty testy, I have to get it to just the right spot in order to get it to move, but I have fwd and reverse. Need to do some searching to get that to work but thanks BGW!

yurtle · 11-07-2012, 06:11 AM

Be careful if your FNR isn't getting a consistent good connection. If it gets a weak connection, that could cause overheating and ultimately FNR failure.

79camaro · 11-07-2012, 09:02 AM

How would I determine if it is getting a good connection or not?

11-04-2012, 06:19 PM	#2
Taykol Getting Wild Join Date: Oct 2012 Location: Homestead Florida Posts: 80	Re: 92 Marathon You should have full battery voltage on the battery side. If 19 is full battery voltage, then charge those new batteries to full, around 38.3 volts. Give some readings of battery voltage and the other tests.

11-04-2012, 07:44 PM	#3
79camaro Getting Wild Join Date: Oct 2012 Location: Austin, TX Posts: 83	Re: 92 Marathon my bad. I was using the voltage from the battery next to the solenoid as the reference voltage. I get 37.2 v on the battery side, and 32 v on the controller side. Thanks in advance!

11-05-2012, 11:11 PM	#5
79camaro Getting Wild Join Date: Oct 2012 Location: Austin, TX Posts: 83	Re: 92 Marathon Thanks Johnnie! I am only getting 35 volts when the solenoid clicks, and definitely not a smooth transition from 35-0! Thanks for the wiring diagram, I am going to check out the high current loop tomorrow and report back

11-06-2012, 05:39 AM	#6
JohnnieB Techno-Nerd Join Date: Jun 2011 Location: West Virginia Posts: 19,654	Re: 92 Marathon Sounds like three problems. 1. Not getting full battery pack voltage between B- & M- when solenoid first clicks. That means there is some resistance somewhere in high current loop. You said the solenoid is new, so it is probably good. That leaves the F/R switch contacts, all the cables high current cables and connections. 2. Not going smoothly from full pack voltage to zero. That is probably a dirty wiper on the throttle potentiometer. Pull the black and white wires off the small terminals and measure between the wires with an ohmmeter. Should smoothly go from about zero to about 5,000 Ohms. Some spray cleaner and working it back and forth a few time might clean it up a bit. Otherwise, it will have to be replaced. 3. Motor not spinning or trying to spin when voltage between B- & M- when from 35V down to zero. (You didn't mention whether it did or not, so I'm just guessing it didn't.) You did say that the motor will spin when voltage was applied directly to it, so the cause of this problem is likely the same as #1 above. Basically, the motor runs, so it is okay and the controller is doing what it is being told to do, but erratically, probably due to an erratic throttle input. When you find and fix the high resistance in the high current loop, the cart will probably run, but be a bit erratic due the throttle pot issues.

11-06-2012, 09:20 PM	#8
79camaro Getting Wild Join Date: Oct 2012 Location: Austin, TX Posts: 83	Re: 92 Marathon Johnnie! Your the man. That wire from the FNR switch was it. I replace the missing wire and just got back from a cruise around my street! The fwd reverse is pretty testy, I have to get it to just the right spot in order to get it to move, but I have fwd and reverse. Need to do some searching to get that to work but thanks BGW!

11-04-2012, 03:58 PM	#1
79camaro Getting Wild Join Date: Oct 2012 Location: Austin, TX Posts: 83	92 Marathon I've been trying to bring a 92 marathon that's been sitting for a few years back to life. These forums have been a lifesaver! I've found most of the troubleshooting from searching, but now I am at a stopping point. I've put in new batteries, replaces the solenoid, and have confirmed the motor works by wiring it directly to a spare battery. It seems I have all the voltage in all the right places, but I am unsure how to check to see if the controller is shot? The other thing I am unclear about is the controller side of the solenoid (the two large opposing posts that is) is reading 13 volts, the battery side is reading 19 volts. I did change out the resistor too. Any ideas? Time to try a new controller?

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11-07-2012, 06:11 AM	#9
yurtle Gone Mad Join Date: Oct 2009 Location: Buford, GA Posts: 8,988	Re: 92 Marathon Be careful if your FNR isn't getting a consistent good connection. If it gets a weak connection, that could cause overheating and ultimately FNR failure.

11-07-2012, 09:02 AM	#10
79camaro Getting Wild Join Date: Oct 2012 Location: Austin, TX Posts: 83	Re: 92 Marathon How would I determine if it is getting a good connection or not?