Troubleshooting a 1996 DCS Controller/Solenoid Issue

[kayakmike]

We have a 1996 EZ-GO TXT DCS. When we bought it a few years ago, it would occasionally stop running, but if we come back to it in a day or two sometimes it would just start working again and sometimes it would still not run. A year or so ago I went through the troubleshooting steps in the forum sticky and it pointed to a solenoid issue. I replaced the solenoid, and it worked fine for a month or so then stopped working again. And I let it sit until I had some time to work on it more.

I opened the cart up last week and walked through the troubleshooting steps. Again it pointed to a bad solenoid. I bought a new solenoid which arrived today. I installed it in the cart, and when I tried to start the cart, the solenoid clicked the first 2 times I pushed the pedal, then it stopped clicking.

I just checked the original solenoid as well as the one I just took out today. Both are reading 150 ohm across the coil, both coils close when I apply 36V to the coils, and I have open circuit across the mains with the coils de-energized and closed circuit when the coil is energized. This appears to show the solenoids are working correctly. I haven't fully disconnected the one I installed today, but my guess is it will work the same.

Here are the voltages I'm reading at various parts of the system:

• Vref = 36V (at battery and at B+ of controller)
• B+ = Vref

Solenoid Coils: 7.4V on both posts
Solenoid Posts: Vref on both posts

Controller Pins

• 1 (ITS output) = 0.44V
• 2 (ITS Input) = 14.2V
• 3 (Reverse Alarm) = Vref (FWD), 1.5V (REV)
• 4 (Reverse) = 0V (FWD), Vref (REV)
• 5 (pedal switch) = 0V pedal up, 4.9V pedal down
• 7 (solenoid coil) = 7.4V pedal up, 4.9V pedal down
• 8 (n/c)
• 9 (logic power) = Vref
• 10 (aux power) = Vref

I disconnected the wires going to the solenoid coil. Vref has gone up to ~37V. Now I'm seeing on those wires that were on the coil:

Wire on one side of coil:

• Blue (pin 7): 0V

Wires on other side of coil:

• YL/WT (key switch): Vref if on, 0V if off
• RD (pedal micro switch): 0V
• YL (pin 6): 7.4V (if in RUN mode/controller powered)

Is this pointing to a controller issue on pin 6? The diagnostics don't mention testing pin 6, but it looks like this is what is pulling the solenoid coil to ~7.4V. What should the normal voltages be on pin 6 or the solenoid coils? Does the controller need to be replaced?

[scottyb]

See test 5.
I believe pin 6 should have refV when key on, in gear, & pedal is depressed

[JohnnieB]

The voltage on the solenoid coil is bad.

With key on and direction selected, you should have Vref on both small terminals.

When you push pedal (applying Vref to Pin-5), the controller connects Pin-7 to B-, so the small terminal with the blue wire on it should drop from Vref to 0V and the solenoid should click.

I suspect you have a bad reed switch.

Bypass it and if that doesn't get Vref to the solenoid coil, check the rest of the circuit highlighted in red on attached schematic.

The voltage readings given tells me there is excessive resistance somewhere in the red highlighted circuit, which consists of 4 switches and a few lengths of wire connecting them in series. The reed switch is the weakest link, so it is the most likely suspect.

[kayakmike]

Thanks for the replies.

I figured it should be Vref, but when everything is connected together it was measuring 7.4V.

As I mentioned, I disconnected the wires connected to the coil. Everything shown in RED in the attached diagram measures Vref. The purple line (yellow wire to controller pin 6) shows 7.4V. The green line between the controller and pedal microswitch shows 0V (I think this is an input to the controller if the pedal is pressed, so since there is no voltage coming to it from the disconnected red wire at the coil, 0V would be expected).

When the wires are connected to the coil, the coil shows 7.4V, so it looks like the yellow wire/pin 6 is pulling the voltage down (since everything on the key switch side shows Vref when disconnected).

I ran a continuity test across the reed switch and there is no resistance.

Thinking this through a bit more, they don't really specify a test for pin 6 (key switch). There should be a test between test 3 & 4, with the key on (key is off for test 3), but pedal off (pedal microswitch is depressed for test 4). I'm assuming that pins 4-6 on the controller are inputs (i.e. pin 6 IDs if the key is on, pin 5 IDs if the pedal is pressed, pin 4 IDs if the direction is set to reverse). If the controller has an internal failure on pin 6 and failed to 7.4V, then it is no longer sensing if the key on and further creating problems since it brings everything that is at Vref on the key side down to 7.4V.

I could try and reconnect everything together without the yellow pin 6 wire connected to the coil. In that case the controller will always see high on pin 6 (since it's internally failed to 7.4V), so if it's an input it will always think the key is on. Any downside to trying that?

Originally Posted by JohnnieB

The voltage on the solenoid coil is bad.

With key on and direction selected, you should have Vref on both small terminals.

When you push pedal (applying Vref to Pin-5), the controller connects Pin-7 to B-, so the small terminal with the blue wire on it should drop from Vref to 0V and the solenoid should click.

I suspect you have a bad reed switch.

Bypass it and if that doesn't get Vref to the solenoid coil, check the rest of the circuit highlighted in red on attached schematic.

The voltage readings given tells me there is excessive resistance somewhere in the red highlighted circuit, which consists of 4 switches and a few lengths of wire connecting them in series. The reed switch is the weakest link, so it is the most likely suspect.

[kayakmike]

Looks like I've got it running.

Before bypassing the yellow wire on the coil, I ohmed out the entire line from battery to controller pin 6. The key switch had some resistance on it (~100ohm). Still beeped on the meter when I checked continuity the first time. I swapped it out with a toggle switch, connected everything back and it runs now.

For others who may have a similar issue in the future:

• If the key switch is off, pin 6 shows 7V (and so does both sides of the solenoid coil).
• If the key switch is on, it shows Vref.

Thanks again for all the assistance.

[scottyb]

So it was a bad key switch?

[kayakmike]

Yes. Now I have the key switch on the bench and it's showing ~80ohm when on. The 7V on controller pin 6 was confusing things, especially after disconnecting from the solenoid coil and seeing Vref at the coil from the key switch.

Originally Posted by scottyb

So it was a bad key switch?