Toyota 8BRU18:
Initial safe test failure on 9BRU18

Hi all

I am working on a Toyota reachtruck 9BRU18, with lack of use but that worked near the sea and let in outsides without any roof protection for some time. Is almost new just degradated by environmental conditions.

The issue is that with battery pack at 36V, once I turn on the EPO and turn on the ignition switch:
1. Display turns on with its beep and initialize safe test.
2. Suddenly it stops at step 4/27 and displays Code FH FN (call service), without any error displayed.
I checked both Curtis controllers (Traction/Hyd) and non of them were receiving any power supply. Neither MPC/STR contactors were activating. I followed the cables and found out that Controllers signals came from a electric PCB board with 4 relays and fuses which were fine and operative.

I am working in blind, Does any one have any information related to this model: Service manual with diagrams or at least from previous model 8BRU18 to work on it, or at least any help.

Thanks
  • Posted 28 Apr 2021 03:55
  • Discussion started by yandier_m
  • Havana, Cuba
YMG
Showing items 1 - 2 of 2 results.
Thanks for reply

I checked battery level and didn´t drops down after key switch on. Neither any of the controllers went on because none of them receive any supply, just the MCU goes on but showing no error.

I noticed that small PCB board installed on the top of the MCU is the one in charge of suplying 36V to traction/hyd controllers through its PCB relays conmutation. I checked and detected 3 circuit lines open and restored them, re-test and again the same problem.
Now I also detected that aditional circuit line in the PCB from a PTC thermistor to MCU input was open, I will restore it and check again.
One question on these Toyota models what´s the nominal working voltage for the battery pack?. Curtis says from 31.4 to 37.6 and right now my battery is at 35.4V.
This question is because even when nothing is happening at the forklift and any controller is going on, basically because MCU is not putting activation signal: +-36 on the top PCB board for relays actaution. Battery level displayed is at minimun.

Also where is FU10?. I just have FU5-8 at the PCb board and the power fuses at the contactors output (MPC/STR)

Is there any way that the MCU not detecting PTC value determine to not initialize anything?

Best regards
  • Posted 29 Apr 2021 06:29
  • Reply by yandier_m
  • Havana, Cuba
YMG
Check what battery voltage drops to when turning on keyswitch. Also check fu10
  • Posted 28 Apr 2021 04:36
  • Reply by Triggs
  • California, United States

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