Toyota Forklift 8FG(D)U15-32, 8FGCU20-32 Electrical System Troubleshooting

Online PDF Toyota Forklift 8FG(D)U15-32, 8FGCU20-32 Electrical System Troubleshooting

1.Disconnect the battery plug before connecting or disconnecting each connector or terminal.
2.When disconnecting a connector, do not pull the wire harness but hold the connector itself and pull it after unlocking it.
To connect, push the connector fully until it is locked in position.
3.Bring a tester probe into contact with a connector terminal from the rear side of the connector (harness side).
4.If insertion from the rear side is impossible, as in the case of a waterproof connector, bring the tester probe carefully into contact with the terminal so as not to cause deformation of the connector terminal.
5.Do not touch connector terminals directly with your hand.
6.When bringing tester probes into contact with terminals that voltage is applied to prevent two tester probes from coming into contact with each other.

When any trouble occurs, first inspect the connectors and wire harness of the related circuit according to the following procedure:
Continuity Inspection
1.Disconnect the connectors at both ends of the corresponding harness.
2.Measure the resistance between corresponding terminals of the connectors at both ends.
Standard: 10 Ω or less
•Measure while jiggling the wire harness up and down and sideways.
•Open circuit at the wire harness occurs rarely partway through a vehicle wiring but mostly at connectors. Inspect especially the sensor connectors with sufficient care.

Short Circuit Check
1.Disconnect the connectors at both ends of the corresponding harness.
2.Measure the resistance between the corresponding connector terminal and frame. Be sure to inspect the connectors at both ends.
Standard: 1 MΩ or above
Measure while jiggling the wire harness up and down and sideways.
3.Measure the resistance between terminals of the corresponding connector. Be sure to inspect the connectors at both ends.
Standard: 1 MΩ or above
The wiring may short-circuit due to pinching by the body or defective clamping.

Visual and Contact Pressure Checks
1.Disconnect the connectors at both ends of the corresponding harness.
2.Visually inspect that there is neither rust nor foreign matter trapped at connector terminals.
3.Inspect that there is no looseness or damage at the crimped portion. Also, lightly pull the wire harness from the connector to check that it does not come off.

4.Insert a male terminal same as that of the connector terminal to a female connector and check the drawing force. Defective contact may exist at a terminal where the drawing force is less than that of other terminals.
Even if there is rust or foreign matter trapped at the terminal, or the contact pressure between male and female terminals is low, abnormal contact condition may be changed to normal by disconnecting and reconnecting the connector. In this case, disconnect and reconnect the connector several times, and if a fault occurs even once, then consider the terminal may have a defective contact.

It is extremely risky to begin troubleshooting for the 4Y engine on the basis of results only. It can lead to mistaken corrective action, wasted time, and sometimes to an increase in abnormalities. Therefore, ask the customer about detailed information on conditions around the time a problem occurred, based on the following.
Diagnostic Procedure
First, it is necessary to be informed of the "fault history and service history" for the vehicle, and then to gather definite information about the fault occurence such as "when", "at what times", "in what places", "during what operations or actions", "what happened afterwards", and “frequency of occurrence”.
Also, try to recreate the conditions for the fault occurence. (a. Recreation impossible  b. Recreation possible: in what condition?)

8FG(D)U15-32, 8FGCU20-32 
There has been a main wiring harness change (part # 56011-U2241-71) on the 8-Series I.C trucks with the synchronized steering option (E72A).  The connector (O4) for the synchronized steering solenoid has been moved from the left hand side harness to the main wiring harness.  If the harness is not installed correctly, then error code 73-1 will become active. 
The Green and White-Black wires that connect the SAS/OPSS controller to the steering solenoid no longer go through pins 19 and 20 at the brown AO1 connector.  The Green and White-Black wires now stop short of the AO1 connector and have their own connector that comes out of the harness just before the junction block connectors.  This connector is a black 2-pin connector with a black terminating plug on the end. 

7FBCU15, 7FBCU18, 7FBCU20, 7FBCU25, 7FBCU30, 7FBCU32 7FBCU35, 7FBCU45, 7FBCU55, 7FBCHU18, 7FBCHU25 7FBEU15, 7FBEU18, 7FBEU20, 7FBEHU18, 7FGU15, 7FGU18 7FGU20, 7FGU25, 7FGU30, 7FGU32, 7FDU15, 7FDU18, 7FDU20 7FDU25, 7FDU30, 7FDU32, 8FGU15, 8FGU18, 8FGU20, 8FGU25 8FGU30, 8FGU32, 8FDU15, 8FDU18, 8FDU20, 8FDU25, 8FDU30 8FDU32, 7FGCU15, 7FGCU18, 7FGCU20, 7FGCSU20, 7FGCU25 7FGCU30, 7FGCU32, 8FGCU18, 8FGCU20, 8FGCSU20, 8FGCU25 8FGCU30, 8FGCU32, 7FGU35, 7FDU35, 7FGKU40, 7FDKU40 7FGU45, 7FDU45, 7FGAU50, 7FDAU50, 7FGU60, 7FDU60, 7FGU70 7FDU70, 7FGU80, 7FDU80, 7FGCU35, 7FGCU45, 7FGCU55 7FGCU60, 7FGCU70 
All three error codes are for the same condition.   
A5 is for sit-down electric trucks (Class I) 
A5-1 is for 8-Series internal combustion trucks (Class IV & V) 
1-1 is for 7-Series internal combustion trucks (Class IV & V) with OPSS (Operator Presence Sensing System) 
This system was implemented in 2005.  The OPSS is required to check for a malfunctioning or bypassed seat switch circuit.  To do this, the system stays active even when the key is off and monitors the seat switch.  If the seat switch stays closed for more than 15 minutes with the key off, the system assumes that the switch has malfunctioned or been bypassed.  The code will stay active until the system sees the seat switch circuit cycle open/closed, then will automatically clear. 
The most common cause for these seat switch codes is an operator staying in the seat.  If an operator stays sitting in the seat with the truck turned off for 15 minutes, they will trip the seat code.  Examples have been operators taking a break, lunch period, or filling out paperwork while sitting on the truck with the key off.  The dealer has been called for a seat switch code and when the technician arrives, the code has cleared, but is stored in memory.  This is because the operator left the truck while waiting for the technician; this cycled the seat switch and cleared the code.  In many cases, the seat switch has been replaced unnecessarily due to this occurrence.  Further information concerning these codes can be found in the following manuals: 
7FBCU15-55 ►OPSS Manual CU335 page 3-9 
7FBEU15-20 ►OPSS Manual CU341 page 1-10 
7FGCU15, 18, S20 ►OPSS Manual CU042 page 1-19 
7FGU15-32, 7FDU15-32, 7FGCU20-32 ►OPSS Manual CU040 page 1-18 
7FGU35-80, 7FDU35-80, 7FGCU35-70 ►OPSS Manual CU041 page 1-17 
8FGCU15, 18, S20 ►Service manual 00700-X8880-71 page 19.1-82 
8FGU15-32, 8FDU15-32, 8FGCU20-32 ►Service manual 00700-X8880-71 page 19-111 

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