2003 48v Club Car Solenoid Loosing Ground

[gtistiffler]

2003 48 volt DS Sepex Curtis 1510-5201 controller.
All new batteries 1/15/18
Pack Voltage 51v
Previous owner bypassed OBC by disconnecting black wire from it and running straight to #6 neg and bought an auto shutdown charger (Links).

Just bought this and trying to figure out it's issue.

If you let it sit say overnight, you can drive it maybe a mile and it will shut down. Turn key off then on and solenoid clicks on then right back off. Can hear the two clicks. It stays like this for awhile, up to an hour.

*I have tested the mico switch in MCOR by backprobing and monitoring voltage and when it acts up still have 48v coming from it.
*Sweep tested the potentiometer and it sweeps fine with no drop outs, etc while driving
*Solenoid stays on/comes on if I ground - small post of solenoid (blue/white wire to controller) when this happens (controller is cutting out path to ground when this happens)
*F/R switch has continuity when this happens
*Key switch working normally when this happens
*Ohm motor widings they test good and also not shorts to case
*Reverse buzzer still working when happens
*All connections/wires look good. Pulled loom from whole harness and inspected
*Tow/Run switch still has continuity when happens

I was reading some of the stickys and noticed some people say there is more to bypassing obc than just bypassing the black wire. Prior owner still has the obc connector plugged in. Could this cause it to go into lockout mode and cause this issue? Thanks for any advice!

Keith

[Sergio]

If the OBC is still connected and it cannot sense the cart charging, it will cause problems.

Assuming this is an IQ cart, Serial number starts with AQ03, You need to connect the Blue and White wires at the OBC 6-pin connector as mentioned in the sticky.

That will provide the signal to the Controller that the charger is "not connected" and the Controller will not initiate a lockout by removing the negative activation from the Solenoid.

[gtistiffler]

Thank you for your quick reply. It does start with AQ03 and those wire are not connected to each other. I will try that and let you know.

[gtistiffler]

Well, still acting up. Grounded solenoid straight to ground and drove it home that way but it started to surge and slow down etc.

[gtistiffler]

Took mcor off and it’s looks to be an aftermarket one. No part number anywhere. Anyway, slowly turned and monitored resistance of potentiometer and it has an obvious open/drop out between 3.5-4K ohms. Gonna get a good one and go from there

[gtistiffler]

Well, took apart mcor and fixed it. Still having issues. Weird thing is...if I unplug speed sensor when it fails it’ll let me drive in limp mode. Bad speed sensor??

[Sergio]

Are You saying the Solenoid clicks when You turn the key ON without pressing the pedal?

If so, You have other problems as the IQ controller requires a lot of inputs before it will turn the Solenoid ON.

If You hard-wire the negative side of the solenoid (blue/white wire connection) to negative, the controller will only run at 1/2 speed as it detects a "main welded".

You definitely need the blue and the white wires at the OBC 6-pin permanently connected to by-pass the OBC lockout.

How did You fix the MCOR, what was wrong?

The best way to check the speed sensor is to push the cart by hand and see if the Controller detects movement and tries to stop.

If You hear the reverse buzzer sound but the cart is not offering resistance to push, the Controller field driver likely failed.

[gtistiffler]

No, I meant I disconnected blue/white wire and ran a jumper to ground to activate solenoid to get me home.
...but when I did that, it drove for a second then dropped out again. So I unplugged the speed sensor and cart then would move while disconnected obviously in limp mode. Could have been coincidence, not sure.

I took the mcor apart, desoldered the board from the two plugs so I could pull it apart. The potentiometer was cleaned and all the “legs” were adjusted to make sure they made full contact with the resistor traces on the board and then I reassembled/resoldered everything and glued cover back on. Experienced no more drop outs in resistance while testing on bench.

I appreciate your help. This is my first cart. Starting to suspect controller issue....

[Sergio]

That makes sense now, one thing you are experiencing is a "main drop-out".

The early IQ models had a bug where the Controller would think the main Solenoid opened by itself.

It was caused by the cart going into Regen and where the voltage is sensed.

The solution was a part called "main drop-out harness".

You can either buy one from a site sponsor like: www.RevolutionGolfcars.com

Or you can install your own 10 amp diode in the power feed right before the Tow/Run switch.

This is a Precedent wiring diagram but You can see the diode before the Tow/Run switch:

[gtistiffler]

Actually ordered that harness from him last night. Fingers crossed...
Thanks again!!