Club Car Precedent Light Harness causes cart to run slow

[Blackdogracing]

The accessory plug was another cart, the only other change to this cart was I did add a high speed magnet. They didn't tell me whether they did any volt readings. Could this in anyway affect the speed sensor. Based on what I'm reading in other posts the limp mode seems to be typical of a bad sensor.

[Sergio]

Anything that causes the controller not to sense pulses coming from the speed sensor would cause limp mode. It could also be caused by excessive noise in the wiring producing interference....

If I understand it correctly, when the converter is off the cart runs normally.

Do all accessories work correctly when the converter is on?

[Blackdogracing]

Everything works fine with the converter on. The shop told me they unplugged the turn signals and brake lights separately which did not take the cart out of limp mode. Only when the gray wire from the bucket harness to the main harness was disconnected did the cart return to normal speed.

[Sergio]

Most of the high amperage dc voltage reducers used in golf cart are "Buck" converters. They ussualy generate a lot of noise due to their high frequency operation. The converter internal filters are supposed to keep that noise from entering the circuit.

I don't know how to verify that without having an oscilloscope attached to the converter input and output lines.

Perhaps you can ask the shop to plug the gray wire back and unplug the converter itself from the circuit to see if the issue is caused by the converter.

[teecro]

WAG While disconnecting the power wire seems to clear the issue could it perhaps be something to do with the speed sender ground being used to complete a circuit? The Curtis 1268 that I installed made it clear that any items that might have been grounded through that wire would cause faults....

[Sergio]

That is specific to the Excel carts where the ground to the speed sender is shared with the black/yellow wire behind the dash as well as the Throttle.

Since he said he installed a speed magnet, it must be an IQ cart, they have a separate ground for the speed sender.

That is also an afterthought from the 1268 conversion harness, it should not be necessary if they used the correct pinout on the controller connector.

[Blackdogracing]

My plan at this point is when I get the cart back is to first do the speed sensor test just to be sure they didn't miss that. Question wouldn't the IQDM pick up a bad sensor? Secondly I will replace the voltage reducer with another type. Any other suggestions if these changes don't rectify the issue?