Your measurements are interesting. They definitely
show some problems.
Wire # 5 to #29 - Readings are what they should be
except for the Key off voltage of 19.6. Should be zero. Where's that voltage
coming from? You said the seat switch was disconnected. Where are the wires
located that were attached to it? Are they possibly laying on top of the
batteries where they might be making contact with a battery
Wire # 34 to # 29- Key off voltage is zero as it
should be. Both the key on voltages fwd. & rev. should be 37+
volts.Indicates a problem with the start switch in your speed control(should
be closed in the home position).If it's working properly, either RTN or RTNR
should pull-in when the keyswitch is turned on.You might want to check this.
Pedal down fwd. and pedal down rev. voltages should stay at 37+. Voltage
drop indicates a possible problem with contacts on both RTN or RTNR relays
or a poor connection at them.
Wire# 23 to #5- All the voltage readings are what
they should be for a normal start of your tractor. Interesting to note that
the only difference between this and the first pair of wires is that the
seat switch, brake switch and thermal in the motor are between them.Since
all of these are either bypassed or closed, the voltage readings should have
been the same. You might try putting a jumper from wire #23 to #29 and
repeat the first set of measurements to see if they now
Wire #23 to #34- Key off voltage should have been
zero. Key on Voltage forward and reverse are correct; indicating your start
switch is in the home position. Pedal down fwd.and rev. should both
remain at 37+ volts. Both the RTN and RTNR relays should have energized, but
if they did, neither one passed voltage from wire #5 to wire #34 indicating
a possible problem with a contact or connection.
That's a good start! Gives you a chance to check
somemore on your next opportunity. If you want me to contact you again by
phone, send me an email. Next week our plant has it's annual maintenance
shutdown, so I'll be in the plant most of the week.
||Key off Voltage
||Key on Voltage FWD
on Voltage Rev
||Pedal Down Fwd
||Pedal Down Rev|
||31 to 24
||26 to 17|
I'll be back in the
office Monday afternoon.