Computer Control Module

Greetings.
My car is a 92 DOHC MultiPort Fuel Injection, Automatic with 200,000 KMs.
Until recently this car was extremely reliable and very fuel efficient.
Burned about a Litre of Oil every 1,000 KMs. Then the Trouble started.
First, the Engine began to Overheat. The Cooling Fan would not start. I
replaced the Coolant Temp Sensor unit. The Cooling Fan still does not start.
Had to run a separate power line to the Cooling Fan with a manual switch in
order to at least be able to drive the car. This is inconvenient, but not a
show stopper as far as I care. But it gets worse. The Car has begun to run
EXTREMELY rich. Fuel consumption is unbearable. Black Smoke in great
volumes. The Service Engine Soon light used to come on sometimes when the
engine used to over heat, but it has not come on at all recently. I tried
reading the Computer Trouble Codes with no luck. There are no codes stored
in the CCM. All I get is the Code 12, Diagnostic Mode Enabled. Nothing
else. The car hesitates under acceleration, wants to stall when leaving a
red light, and will over heat if I don't use the manual Cooling Fan switch I
installed. Service Engine Soon light does not come on when Overheating. I
Checked the EGR Valve, it does not stick, and holds a vacuum well. The PVC
Valve was changed. The Injectors are all clicking smoothly without any
interruptionos at any RPM. This has been a great car so far, in spite of the
High Mileage. It was well taken care of obviously, and has been very good
until only very recently. What can happen to mess up a car so badly so
quickly. What could the problem be? Can the Computer Control Module itself
be to blame? How can you check that item for reliability?
Any comments would be greatly appreciated. Thank You.

 

A bad coolant temperature reading (too low) could cause the rich running and
inoperative cooling fan. I know you replaced the CTS, but it could be
another problem, like a wiring or connector problem. (Also, some cars have
one sensor for the ECM and another for the temp gauge, are you sure you
changed the one for the ECM?)

A bad ECM is possible, but one should generally eliminate all other causes
because they're not a common source of trouble.

 

A bad coolant temperature reading (too low) could cause the rich running and

Sounds like the CTS to me also. Are you sure you replaced the one with 2 wires
going to it? Also, I have heard of them being bad from the factory......

The reason your car is acting the way it does is since the CTS is always
telling the computer the car is cold, the computer makes the fuel mixture rich
and will never turn the fan on.

 

UPDATE:
This NewsGroup is GREAT!
I replaced the Engine Temperature Sensor for the ECM. There are TWO Engine
Temperature Sensors on this Vehicle. One for the Gauge, and one for the
Computer Module. Go Figure! My cost $28.00 Taxes Included.
This instantly resolved the issues I was having. The Black Smoke is gone,
and the Cooling Fan has started turning on anf off on its own again! Gas
Mileage is back to expected levels.
The car is running Top Notch again!
I really like this car, considering the Mileage it is in excellent shape,
and continues to be very reliable, all things considered. I would buy
another Saturn in an instant. Thank You All.

Guy Trudeau
Winnipeg, Manitoba, Canada
http://go.to/gtrudeau

 

Bonjour. Another Winnipegger here. Which dealership do you go to?