General Discussion

[Rainwater3417]

I am having a problem nailing down the cause of this fault code 1405.6 (transmission solenoid #5 high voltage).  Originally I checked the solenoid and found the resistance to be way too low, so I replaced it, thinking problem solved...not the case.  I have tested the wiring harness all the way back to the TCM and all the wires have correct resistance readings.  The symtom is the controller defaults to Neutral in 3 and 4 forward and in 3 and 6 reverse, which, of course are the only gears that solenoid #5 is used on  (also getting trans fault light in Neutral and Park, but only because #5 is used there too).  I am working off of a schematic and have come to the conclusion that the TCM may be bad and sending the wrong voltage to #5 when requested,  I have checked my shifter and it seems to be working fine.  It is requesting the right gears.  have also swapped the solenoid spools in the control valve and have eliminated that as a cause as well.  My question is, has anybody else run into this and would a bad TCM cause this symptom? Thanks for any help.

[Cat_Tech · Accepted solution]

The code is actually for current above normal.  If you have replace the coil and it is within spec of 8.7 ohms.  and all the wiring is ok, with low resistance, then I would lean toward the ECM.  Does it do it all the time?  or intermittent?  I have had ECM's fail in wierd ways, never had one on a grader, but I do not see that many of them either.

[roalja]

This DTC 1405-6 is for current high not voltage high.  Is that the DTC you have or do you actually have 1405-3 (voltage high)? 

There are many things that can cause this circuit to over current.  The most likely is a wire harness short to a ground source.  For instance, the wiring rubbed against a metal edge and cut into the wire somewhere.  This will likely be intermittent so it probably won't show up on any resistance checks.  Inspect the wiring for any places where the harness contacts a metal edge.  Look for damage in these areas.

If the DTC is 1405-3 instead, it is caused by the high side output wire being pulled high (voltage high) by an external source.  The most likely cause of this is water in a connection or a wire to wire short.  Again the Ohm check will not find this.  Inspect the wiring and connections looking for water entry in connectors or signs of melting or abrasion in the wiring.