2012 Hino 338 no exhaust brake

[Tony324]

I can turn it on with the computer but when I flip the switch it says that's its still off so I replace the switch and still the same problem anyone have any info

 

[Hino123]

Make sure the engine rpm is 980 or above, If it has an ABS light on it will disable activation from the switch. Check the relays and verify they are receiving and distributing power.

 

[Tony324]

thanks Hino123 rpms are above 980 no abs or check engine lights. If it was a relay would I still be able to command it on with the scanner?

 

[Hino123]

Are you using DX2 or a generic scanner? Check EVERY!!! fuse in the dash for power and that there is a fuse installed in EVERY cavity that has it. Inspect the relay pictured. It should receive a signal from the switch on the signal side of the relay. If you remove the relay nd look the gold plated pins are for the supply voltage and the others are signal. You need to see if you are getting a signal from the switch at the non gold pins. You should have 12v on two legs of the relay. If you jump the gold pins and the exh brake comes on. I would assume you have an issue on the signal side of the circuit coming from the switch.

 

[Hino123]

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