Each day I help customer's with chipper issues's here's how to test your Valve's.

*Unplug the Auto-Feed Plus 

*Identify the pins on the plug and their function's!

*A-B-C-D=Brown-Reverse wire

* Start the chipper Idle only with the feed bar in the Feed FWD position.

*Using a jumper clip jumper pin's C andD together your feed should stop with a dump valve system==and should feed FWD with a FWD/REV system!

*what does it do? if nothing? is there a break in the wires or blown fuse?

Wiring and HYD. Reverse valve Test with Auto-Feed Plus unplugged using a wire jumper.--------------------------------------------->

Most Industrial engines have either a Alternator or Mag. PU lead to drive the Tachometer! there's several type's 3/4" fine 5/8" and Metric style's. They put out AC voltage when a metal object like a Tooth of a ring gear passes by, the GAP is .010"-.020 for proper signal out. Metal chip's on the tip and out of adjustment, or an open coil winding inside the PU are most of the common problem's. 

Other common valve problems are a 

stuck Valve meaning!

When you apply power to the coil the valve does not function properly?

Internal stuck won't shuttle back 

replace the valve with same or similar.

Test #1 Testing a Mag Pickup sensor

#1 Tech. Call's I receive are the AFP read's 0 when the engine is running!


That 0 show's there is NO SIGNAL or RPM coming into the AFP.

Most repairs are Easy! here are some common things to look for.

* Broken wire>Ground?

* Fuse Blown

* Shorted Hyd. Coil pak >12vdc=2.5A ea.

* Past repair wiring that's incorrect

* Mag. PU shorted open? 

* Test HYD. valve out of circuit        w/jumper clips to a battery.

* Program settings Type 0 vs Type 1?

Reverse valve test using harness and jumper.

Reverse Valve test!

Engine at idle feed bar in Feed FWD position place jumper between C and Brown 1/4" male terminal you should have feed wheel's reversing.


If not trouble shoot wiring or Valve issue's.

Wiring and HYD. Feed Fwd Test with Auto-Feed Plus unplugged using a wire jumper.--------------------------------------------->

Pictured is a typical DIN connector cap

this plugs into the solenoid coil pak 2 wires attach through the cable gland.

Removal of the coil pak is EZ via removal of the plastic nut! 

The coil pak and O-rings slide off the Valve shaft observe how it goes together take pictures of your valve for reference when servicing your equipment.

             Hyd. Valve tests

Most chipper repairs require tools and test equipment!

#1 First determine if it's a Hydraulic problem or electrical?

#2 Sometimes it's just a Program issue where the settings are wrong!

Needed are a Multimeter, Wire Jumper clips, spare 16-18g stranded wire, fuses, solder and I use a portable torch, Misc hand tools, shrink tube.

Hyd. Valve issue's

Coil pak removal

coil pak DIN connector

Pictured Left is a Hyd Valve DIN connector.

A ground wire is needed on one terminal.

A feed wire from the Auto-Feed Plus connects to the other terminal Fused!

Auto-Feed Plus out of circuit test!

Two common tests you can make, testing feed function's on your chipper using the wiring harness on your machine!

Jumper the plug as pictured for FWD test.

Shorted coil pak's are common

they draw excessive power and heat up

test with your Multimeter on OHM's or

test with your meter on AMP's setting for current draw!

A typical 12vdc coil draws 2.5A dc.


Test the PU out of circuit using your Multi meter on Ohms most 3/4 fine thread Mag. PU range 130-160 Ohm's good.


Two terminals are used!

The terminal's that look like a U are the coil pak winding lead's.

apply 12vdc to one terminal

apply ground to the other terminal 


Place Jumper in C&D set engine at Idle w/feed bar in Feed FWD, with a DUMP Valve system your feed wheels should stop! remove jumper feed wheels start FWD again.


Jumper C&D with a FWD REV Valve at Idle Feed Bar in FWD Position you should get Feed wheels turning FWD.

If you don't get those result's then trouble shoot wiring or valving issue's.