Engine Protection Module (EPM), 1993 Grand Marquis

[Rick Mayer]

I am still working on an Engine Control Module (ECM) issue with the Cat 3176 engine powering our 1993 Grand Marquis(90000 miles), an intermittent Check Engine Light, Engine Overheat, but both engine and transmission temps were 185 as always.
  Dave Atherton has been a tremendous asset in helping me understand how the system works and what it can tell you about the health of the engine.  The last piece of this puzzle is the Engine Protection Module(EPM).  Both my Beaver Service Manual and Beaver Owners Manual show this unit, a "Digi-Set", located " behind the dash",and describes it as a protective module provided by Gillig that will shut down the engine if certain perimeters are exceeded.  I have been unable to actually locate this EPM, I have spoke at length with Beaver and Gillig Service and neither could shed any light on where to find it.
  I have taken the RV to a certified Cat Repair Service and they were unable to retrieve any Diagnostic Codes from the ECM, so I was hoping if I can find this EPM, there may be an access port on it to search for fault codes.
  Bottom line, the cruise control will not engage unit fault codes are cleared.  We are headed for the FMCA and all the associated Beaver Rallies in AZ.

[Steve Huber Co-Admin]

Rick,
If you haven't already check in the console to the left of the pilot's chair. They may have placed it there. Just a thought.
Steve

[Dave Atherton]

Rick, my suggestion before you set out going after the engine protection module. One
thing you will need if EPM shuts down engine the engine will not start, you will need a
Cat personally Code to clear the EPM. This code is only avaible from Cat Dealer or is on
your Cat Engine ECM. Would suggest getting your Engine ECM readout/printout and put
the pass code with your records. The EPM code can be cleared if code is avaible with Cat ET.
Dave Atherton Retired Cat Mechanic

[Rick Mayer]

Dave , I will do that.
Thanks
Rick

[Edward Buker]

Rick,

That era Beaver had the overhead console with digital readouts which required that a lot of wiring go to that console. It would make more sense that it would be behind the dash but may possible they put it overhead.

If the manual or experience said it would buzz or alarm, perhaps with the ignition on and the engine not started (no oil pressure), it would make sense that the buzzer gets a signal from the Digi Set and if you locate the buzzer, the buzzer wire feed to that may lead you to the Digi Set.

Check your schematics and see if any wiring that comes from the Digi Set to another dash item can help you trace its location through the wiring. Those were finely built old coaches.

Later Ed

[Rick Mayer]

Just wanted to update the Forum on my EMP issue and lack of Cruise Control.  Finally got the coach to a "Real CAT " repair shop, Butler CAT, 14 locations in North & South Dakota.
     The only EMP port on my coach is on the engine, a Product Status Report gave a Code 84 -10, Vehicle Speed signal Rate of Change, 53 times in one hour.  CAT Tech feels loss of ground to Cruise Control Buffer was the cause of Code 84-10.  He found the Buffer in the frame by the transmission. Replacing the eyelet on the ground wire has fixed the cruise. Parts $11.26, Labor  $951.20