THIEMAN Series TVLR 125A, Owner'S Manual

Page: 25 / 28

25.
TROUBLESHOOTING GUIDE
TVLR125-16 ET
Test Equipment: 1. 0-5000 psi pressure gauge
2. DC voltmeter/ohm meter
3. DC amp meter
4. standard mechanics tools
Note: Please refer to the electrical diagrams and hose connection drawings in the liftgate’s owner’s
manual when troubleshooting. This guide is only for standard Thieman liftgates. Special liftgates with
options other than those in the owner’s manual will require special diagrams for troubleshooting. Read
and understand this entire guide completely before doing any troubleshooting. Certain listed problems
may be related to other problems listed so a comprehensive knowledge is required before proceeding.
1. Problem - Pump motor will not run in the raise mode
Cause Correction
a. Tripped circuit breaker Reset the circuit breaker located within 2ft of the liftgate supply battery(ies).
b. Blown 20A fuse
Replace 20A fuse (s). Each control cord should have a 20A in-line fuse
on the black wire, where it connects to the 2ga. battery cable at the motor
start solenoid.
c. Improper battery
cable connection
or improper ground
connection
The “at rest” voltage for the batteries without the engine running and under
no load should be at least 12.5V, and this voltage should be seen on the
heavy 2ga. battery cable, where it connects to the large terminal of the
motor start solenoid. The minimum voltage between the motor stud and
ground is 10V at maximum conditions, with pump motor, batteries, and
cables under max. load. If the voltage is dropping below 10V under max.
load, bad connections may be acting like resistors and causing larger
voltage drops than expected. Check voltage drops with system under load
at different locations between the liftgate and battery source, to locate bad
connections along the battery cable. Trace ground cable connections also
to locate improper connection(s) along the ground path. Make sure the
ground cable is installed going from the 5/16 tapped hole in the aluminum
pump base marked GND to the liftgate mounting plate (scrape paint to
bare metal for good ground). The ground cable from the batteries to the
frame must be a heavy 2ga. cable that is connected to bare metal on the
frame. Replace any damaged cables and repair any bad connections
d. Defective or
undercharged
battery(ies)
If proper voltage is not present, load test batteries and replace any
defective batteries. The battery(ies) on the vehicle should be that which
has a minimum 180-amp reserve capacity.
e. Defective or
improperly wired raise
switch
Check voltage on the black wire of the control cord near the switch. If no
voltage is present the black wire from the motor start solenoid is loose or
broken and needs repaired. If voltage is present then check for voltage
at the white wire on the switch with the switch in the “UP” position. If no
voltage is present, replace the switch.
f. Defective or
improperly wired
solenoid start switch
Check for voltage on the white wire at the motor start solenoid when the
switch is activated “UP”. If no voltage exists the white wire is loose or
broken between the switch and the motor start solenoid. Check that the
purple ground wire on the start solenoid is connected properly and there
are no bad connections. If there is voltage on the white wire and the coil
does not energize or if there is no voltage on the motor side of the solenoid
or a large voltage drop present across the large terminals of the motor
start solenoid then replace the motor start solenoid.