Model 6210 Maintenance Manual

Troubleshooting Guidelines

General

Block the lift truck so that the drive tire is off the floor whenever a troubleshooting procedure requires turning the truck ON. This prevents accidents caused by unexpected lift truck travel.

Use extreme care when the truck is jacked up for any reason. Keep hands and feet clear while jacking the lift truck. After the lift truck is jacked, place solid blocks or jack stands beneath it to support it. Do not rely on the jack alone. See “Jacking Safety” on page2-8 .

Section 5.Troubleshooting

Electrical Troubles hooting Guidelines

•Broken wiring and shorted conditions (especially those that are close to metal edges or surfaces)

Use a Digital MultiMeter (DMM) such as a Fluke meter for all measurements. Analog meters can give inaccurate readings and load down sensitive electronic circuits enough to cause failure. Make sure mete r cables are connected to the correct meter jacks and that the correct function and scale are selected.

When measuring voltage, connect the positive meter lead to the connector or probe point marked (+) in the test. Connect the negative meter lead to the connector or probe point marked (–).

Whenever measuring resistance, turn the truck OFF and disconnect the battery connector. Battery current can damage an ohmmeter. Isolate the component from the circuit.

For troubleshooting DC electric motors, see “DC Electric Motor” on page5-4

For troubleshooting AC electric motors, see “AC Electric Motors” on page5-9 .

Unless otherwise directed, disconnect the battery connector when you check electrical circuits or components.

Before removing a power amplifier, discharge the amplifier’s internal capacitor by jumpering the + and –terminals with a 100 ohm 25W resistor.

Many problems are caused by a faulty or dirty battery. Make sure the battery is clean. See “Battery” on page7-34

Save time and trouble by looking for simple causes first.

Visually inspect all wiring and electrical components for:

•Loose connections or connectors

•Loose or broken terminals

•Damaged terminals, blocks, or strips

Publication: 1146947, Revised: 12 Jan 2017

For information on pin, connector, and harness connections, see Wiring Harness on page7-47

Shorts to Frame

Shorts to frame is an industry term for unintentional current leakage paths between normally isolated electrical circuits and their metal enclosures.

Shorts to frame may be metallic connections, such as a wire conductor contacting metal through worn insulation. More often, shorts to frame are resistive “leakage” paths caused by contamination and/or moisture.

These leakage paths can result in unwanted electrical noise on the metallic lift truck structure and can caus e incorrect operation.

Section 5.Troubleshooting

Model 6210 Maintenance Manual

Shorts to frame are caused by:

•Accumulation of dirt

•Battery electrolyte leakage

•Motor brush dust

•Motor brush leads touching the housing

•Breakdown in insulation

•Bare wires

•Pinched wiring harness

•Incorrect mounting of circuit cards

Shorts to frame can occur at numerous locations on a lift truck, including:

•Batteries

•Motors

•Cables, wiring, and harnesses

•Heatsinks

•Bus bars

•Solenoids

•Contactors

•Terminal strips

•Switches

•Power panel insulation

•Circuit card mounts

Shorts to Frame Test

To test for shorts to frame:

Electrical Troubles hooting Guidelines 5-2 a.Install another battery in the truck and repeat this procedure from Step 1. b.If the test light does not light, continue to the next step. a.Install another ba ttery in the pallet truck and repeat this procedure from Step 1. b.If the current is less than 0.0002A (0.2mA), go to Step 4. If the current is greater than 0.0002A (0.2mA) and less than 0.001A (1mA), remove the battery from the truck, then continue with Step 4. Make sure the battery case does not touch the truck frame during the remaining tests. a.To identify the cause of the short to frame, disconnect circuit components until the low resistance condition disappears. Do not reconnect components one at a time, but leave them disconnected until the low resistance reading disappears. Prevent disconnected terminals or connectors from touching the truck frame or other conductive surfaces. b.The most likely areas to check are:

1.Turn the key switch OFF and disconnect the battery connector.

2.To test the battery for shorts to case, connect a 12V test light to the battery case from battery B+, and then to the battery case from battery B–. If the light illuminates at all, even momentarily, there is a serious problem with the battery, either external contamination or internal damage. Do not continue until this condition is corrected. The meter may be damaged if you proceed before correcting this condition.

3.Use a DMM set on the ampere function to measure the current leakage from the battery case to battery B+ and from the battery case to battery B– (not truck B+ and B– ). Begin measuring at the highest ampere scale and work toward the lowest. A reading of more than 0.001A (1mA) indicates a serious short. Do not continue until this condition is corrected.The meter may be damaged if you proceed before correcting this condition.

4.With the battery disconnected (or removed and disconnected) from the truck, use a DMM to measure the resistance from truck frame to truck B+, to truck B– (not battery B+ and B–), and to all fuses and motors. A reading of less than 1000 ohms indicates a serious short. Do not continue until this condition is corrected. The meter may be damaged if you proceed before correcting this condit ion. To correct the condition, follow steps a through e.

•Motors

•Heatsinks

•Power cables

•Power circuit components

•Control circuit components

Publication: 1146947, Revised: 12 Jan 2017