Dodg Caravan 1991/3.3l - tachometer

The vehicle mentioned in the title has 300,000 KM. Recently noticed
the tachometer rises smoothly with pressure on the accelerator, but
seems to over-register the engine rpm. The vehicle behave normally in
all other respects and the transmission fluid is bright pink. Could
the pickup or ECM, or TCM be at fault and where and what is the sensor
that generates the tach dashboard display.

Thanks

 

I have had the following in a text file on my computer for several years:


1 The 1.6 and 2.0 liter engines are
manufactured by Mitsubishi, and are also
used in vehicles produced under their name.
The same connection configuration applies.

2 When using pin 43 of the SBEC (Single
Board Engine Controller) as the tach
connection point, the NUMBER OF
CYLINDERS selector on the tachometer is
set to the 4 cylinder position regardless of
the number of cylinders in the engine!

3 In some applications, there may not be a wire
connected to pin 43 of the Single Board
Engine Controller, however the tach signal is
available at this pin.
8
CHRYSLER CORPORATION & MITSUBISHI MOTOR CORPORATION 1
ENGINE CONNECTION DETAILS
LOCATION/CONNECTOR PIN NO. WIRE COLOR
1989 1.6 L IGNITION COIL PACK, 4 PIN 3 WHITE
1990 1.6 L IGNITION COIL PACK, 3 PIN 2 YELLOW/BLACK
1990 2.0 L IGNITION COIL PACK, 4 PIN 3 WHITE
1990-93 3.3L, VIN R SINGLE BOARD ENGINE CONTROLLER 43 2 GRAY/LT BLUE3
1990-93 3.8 L SINGLE BOARD ENGINE CONTROLLER 43 2 GRAY/LT BLUE 3
1991-92 3.0 L, VIN U SINGLE BOARD ENGINE CONTROLLER 43 2 GRAY/LT BLUE 3
1992-93 2.0 L IGNITION COIL PACK, 3 PIN 2 YELLOW/GREEN

 

Also the tach driver board on the gauge cluster had an adjustment pot on it
on my '89 Sundance 2.2. It was probably for calibration.