Re: 91' tech acting up
Backyard Mechanic wrote:
> "Slightly Graying Wolf"
>> No, sorry I should have specified (and yes I meant tach) the tach
>> drops to zero while driving or idling for short periods of time -
>> then the check engine light comes on (presumably because the
>> computer needs to know the RPMs) as soon as the tach jumps up to the
>> correct RPM the check engine light goes out.
> Okay... that's a WHOLE lot different. Does the engine idle quality
> I think the problems have common source and it shouldnt be in the
> tach, It would be in Crank/cam position sensor.. or in the DIS
> module itself.
> It would be very poor engineering for the PCM to look at the tach
> Since the CEL comes on, hie thee to autozone to have the codes read
> out. Make them give you the code numbers, not just the definitions,
> and do a google on the codes and post them here.
The code is #218 "No ignition monitor signal"
The problem did not happen on the way to work today so it made me wonder if
this could be a battery/ alternator problem as it usually happens at idle
under heavy load on the electrical system - A/C, radio, headlights (day time
running lights - Canada).
The guys pissed around with it for an hour or so discounting anything I
said... charging system was 12.1 Volts under full load - Then it happened
with the tester on the battery (it dropped down to 11 volts) until I revved
the engine and the problem went away again (then the voltage returned to
The mechanic then pulled the small plug off of the alternator and duplicated
Looks like all I need is either a new battery or alternator (or both).