Pulldown resistors for TPS MAP

[Walter Petermann]

Bruce Plecan wrote:
> 
...
> 
> >Bruce,
> >what was wrong with using the pots?
..
> My concern is ruining the ecms.  Just I got a real budget, and this
> could get expensive.   For the several minutes so far noting seems
> wrong, but I plan I spending many long hours at this.
> Cheers
> Bruce
> >

  Bruce,
  there's only a couple of ways I can think of that might damage
  the ecm (through MAP and TPS pots).
  i)  If the 5v for the pots does not come from the ecm and is
      on when the ecm power is off. 
  ii) If the 5v for the pots does come from the ecm, but is connected
      by mistake to the pot wiper. When you turn the wiper to
      ground you'd short out the ecm 5v source. ( done that! luckily
      damaged only the pot).
  
  For the ecms I work on (Lucas) there is internal protection for all 
  the above (up to a point..). I'm sure GM ecms are better.

  iii)Static discharge. Before touching any of the ecm wires touch the
      grouded ecm case. Don't know if this actually does anything, but it 
      makes me feel safer. 

  Following all the above, I've had only one mysterious 'death' in over
  600 repairs. 

    Walter