TGO Guys,

My son and I have been troubleshooting our engine trying to determine the Root-Cause of multiple codes from the ECM. The engine was running and we received: 12 (Dizzy Ref.), 21 (TPS Plunger), 23 (M/C Solenoid), 32 (Short Circuit or Baro. Sensor).

While we were studying the Chilton's looking for some answers, we stumbled across a photo of the "Coolant Temp Sensor" (in photo right side). We do not have this sensor hooked up as our sensor's top was damaged and we were told this sensor was only for the electric radiator fan (which we do not have installed). We have a temp. sensor in the Driver's Cyl. Head, it is connected to the harness. We also have a two-wire (yellow & black wire) temp sensor installed in the intake near the thermostat.

Some Questions....
#1 - The Chilton's seems to indicate that the "Missing Sensor" is an integral part of the ECM. Yes/No?
#2 - Could this contribute to the codes we received? The codes were IMMEDIATE.... long before the engine reached normal operating temperature.
#3 - Is there any item that could relates to all of these codes? (i.e. a single common denominator)
#4 - What is the purpose of this and the other two(2) temp sensors?

Any assistance would be appreciated.

Sincerely,
Kurt & Derek

 

I'll admit, I'm not as familiar with the earlier 3rd gens as I am the later models, but the setup should still be the same. Whoever told you that sensor is for the electric cooling fans is correct. That is not the CTS. The only question I can answer for you is #4, and to put it simply:


The sensor in the driver's side cylinder head in between the #1 and #3 spark plugs is the coolant temp. sending unit. It has a single-wire connector on it, and is what the temp. gauge in the gauge cluster in the dash uses to read coolant temp.

The sensor in the front coolant passage of the intake manifold near the thermostat and housing is the coolant temperature sensor (CTS). It has a two-wire connector on it, and as you already know, the CTS is what the computer (ECM) uses to read coolant temp.

The sensor in the passenger side cylinder head in between the #6 and #8 spark plugs is the coolant fan switch. It also has a single-wire connector on it, and is what the electric fan(s) use to read coolant temp.

 

Benm109,
Thanks for the quick response. I'm happy (sort-of) to hear that the information I received about the sensor was correct. We're still reading the books and searching the TGO site for answers to #3.

Funny thing is....... ALL the readings are perfect... Dwell about 30*(+/- 3* to 5*) on the MCS. Voltage at .48 (+/- .003) for the TPS. The car idles poorly and the codes are lighting up like a christmas tree.


Thank you again,
Kurt & Derek

EDIT: I believe you actually answered #1, #2, & #4.