sd electric scooter diagnosis
Cable Adjustment

electric scooter diagnosis

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electric scooter diagnosis

These tests need to be done in order. Skipping a test will not tell you much unless you suspect a damaged part. The tests are only for brushed motors used on 98% of electric scooters.

Important: Brushless motors - should only follow the battery voltage check. Electric bicycles often use brushless motors

pre check - make sure of the following: there are no bare or worn wires. all of the connections are tight and fully seated. all wire tips are fully inserted into the connectors (usually white). charge the batteries overnight.

tools: voltage meter (digital preferred), wrench to remove deck bolts if any, phillips screw driver, 2x 10ga jumper wires, 1x 16ga jumper wire/ paper clip unfolded,

0 - remove the chain (best) or position the scooter so the rear wheel is off the ground and stable

1 - Battery:
Check battery voltage - you should see at least 12.25v per battery. If they are lower than 12.25 you need new batteries. If you have good voltage reading but the scooter will run for only a few seconds try checking the voltage with the throttle on. If the voltage now reads below minimum you need new batteries. also see battery notes (batteries are available here)
note - if you're not able to do this stop, the rest of the tests will not be valid.

2 - Fuse:
Check the fuse it should not be discolored. If it looks good check the continuity of the fuse holder with the volt meter - see fuse notes for location and replacement info

3 - Brake switch:
Check and make sure the brake handle is returning fully when released. If its retuning then disconnect the wires at the controller connection. Try the throttle, if the motor now works you need a new brake handle assembly [ if its not returning loosen the brake lever screw so that the lever returns freely and check to make sure the cable adjusted correctly (see cable adjustment guide)] (get brake parts here)

4 - On/Off Switch:
Remove the switch from its holder so you have access to the wires. Test continuity with the volt meter OR use the paper clip to short the leads and try twisting the throttle. If the motor turns you need a new switch.

5a - Brushed Motor:
Disconnect the motor leads. Using the heavy jumper wires test the motor by connecting the motor leads directly to one of the batteries, if it turns at a constant speed your motor is good if the speed varies a lot or its making noise you will need to rebuild or replace it. (motors are available here)
5b - Brushless motor: (soon)

6 - Throttle & Controller (Brain): see the appropriate section
2 wire throttles - 0-5k throttles should be tested with a volt meter for continuity throughout their range. If your scooter is jerky when accelerating a bad throttle is most likely the cause. If you have good continuity you need a new controller. If its jerky or there is no continuity then you need a new 5k throttle (get controllers here and throttles here)
3 wire throttles are easily tested by disconnecting the throttle connector and shorting the red and black wires using a paper clip or light guage jumper wire. This should produce full speed at the motor, if nothing happens you need a new controller, if you get full speed you need a new throttle. If you do not want to short it follow the 4-6 wire instructions. (get controllers here and throttles here)
4,5, and 6 wire throttles "With your voltmeter, test across the red and black pins coming from the controller. You should see 5V. Connect the red wire to the throttle (you may need to use a jumper) and then start testing the wires coming from the throttle. Check each one against the black pin on the controller. One should give you 5V and will vary (toward 1V) as you twist the throttle control. If none do, you have a bad throttle." source: (get controllers here and throttles here)

If its still not working you need to repeat all of the steps above or take the scooter to a qualified repair shop. If you do not have a repair shop nearby you will want to begin replacing items in order of the tests. The most common part needing replaced is the battery pack, the rest of the parts/tests are organized most common and lowest to highest cost.

battery - sla batteries like to be kept fully charged so whenever you're done riding make sure to recharge them. new fully charged sla batteries will have voltages between 13.25v and 13.5v. as they age the maximum voltage they will charge to may decline. batteries that will only charge to 12.0v are dead and need to be replaced. Batteries have a shelf life of 1 - 5 years depending on quality. expired batteries may not take a charge. If you purchased new batteries and they do not fully charge you need to return them.

controller - most controllers have a minimum voltage cutoff, testing needs to be done with a fully charged working battery pack.

fuse - fuses are generally located in 1 of four places. they can be inline between two batteries, under a cap marked fuse on the side of the battery box, also near the on/off /key switch, or inside a fuse box anywhere inside the battery tray. If your lucky you have a resettable fuse, these are a button usually located on the side of the battery box.
Fuses can be found at auto parts stores. If you have a chinese scooter we recommend you replace the stock fuse holder with one that will accept standard fuses. These are available at auto parts and electronics stores. Make sure to purchase a fuse with the same rating.
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