Coolant gauge out of wack? 01 STS

[Babydon]

I was on the hwy this morning and the worst thing that could've happened came about...

My coolant temp jumped to HOT and a couple warnings came up - coolant over heating and engine idle.

I was about to go nuts when a few seconds later it jumps right back to normal (temp) and all warnings turn off as well.

I pull over and see no signs of over heating, no smoke, no excessive heat, no smell.

I resumed driving to get to work and everything seemed back to normal.

Was this just a sensor issue? Please God tell me it is... although it will probably be JimD.. lol

Thanks team!

[BodybyFisher]

Check for codes first, you may find a code that leads us in the correct direction, this is undoubtedly ECT related (engine coolant temperature sensor). It sounds like it or its wiring may be at fault, Mike

[Babydon]

Check for codes first, you may find a code that leads us in the correct direction, this is undoubtedly ECT related (engine coolant temperature sensor). It sounds like it or its wiring may be at fault, Mike

Thanks Mike!

I'll check codes and post in this thread later.

Mark

[Babydon]

Here are the current codes that popped up - same ones I've had ever since I bought this car!!!

PCM P0741

PCM P1860

Another thing I noticed is that my fuel gauge is empty - I just filled up last night. :S

[BodybyFisher]

Oh boy, no ECT sensor code....

Here are a few schematics to look over, notice the coolant gage and fuel level gages they are on the Class 2 bus. I dont see common grounds but that is a thought. How is your battery?, and battery connections?

PCM Sensor Signals

PCM Grounds

PCM Signals

Check this out:

Instrument Panel Cluster (IPC) Description and Operation

Displays Test

Certain instrument panel cluster (IPC) features are tested when the ignition is turned on in order to verify the features are working properly. The following illuminate briefly or flash at key up:

• The air bag indicator flashes 7 times.
• The ABS indicator
• The brake indicator
• The charge indicator
• The cruise indicator
• The engine coolant indicator
• The engine oil pressure indicator
• The fasten belts indicator
• The security indicator
• The service engine soon indicator (MIL)

Indicators and Warning Messages

Refer to Indicator/Warning Message Description and Operation .

Engine Coolant Temperature Gage

The IPC displays the engine coolant temperature as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the engine coolant temperature. The engine coolant temperature gage defaults to C if:

• The PCM detects a malfunction in the engine coolant temperature sensor circuit.
• The IPC detects a loss of class 2 communications with the PCM.

Fuel Gage

The IPC displays the fuel level as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the fuel level percent. The fuel gage defaults to empty if:

• The PCM detects a malfunction in the fuel level sensor circuit.
• The IPC detects a loss of class 2 communications with the PCM.

Odometer

The IPC contains a season odometer and a trip odometer. Press the RESET TRIP A/B button for greater than 2 seconds in order to reset the trip odometer. The IPC displays the vehicle mileage and trip mileage as determined by the IPC. The IPC calculates the mileage based on the vehicle speed signal circuit from the PCM. The odometer will display 'error' if an internal IPC memory failure is detected. The odometer displays either miles or kilometers as requested by the activation of the ENG/MET button on the driver information center (DIC). The associated indicator (km or MI) illuminates.

PRNDL Display

The IPC displays the selected gear position as determined by the PCM. The IPC receives a class 2 message from the PCM indicating the gear position. The PRNDL display blanks if:

• The PCM detects a malfunction in the transmission range switch circuit.
• The IPC detects a loss of class 2 communications with the PCM.

Speedometer

The IPC displays the vehicle speed based on the information received from the power control module (PCM). The PCM converts the data received from the vehicle speed sensor into a 4000 pulses/mile signal. The IPC uses the vehicle speed signal circuit from the PCM in order to calculate the vehicle speed. The speedometer defaults to 0 MPH (0 km/h) if a malfunction in the vehicle speed signal circuit exists.

The speedometer displays either miles or kilometers as requested by the activation of the ENG/MET button on the driver information center (DIC). The associated indicator (km/h or MPH) illuminates. The speedometer display configuration can be changed as requested by the activation of the DSPL MODE button on the driver information center (DIC) switch. The speedometer can be configured in the following formats:

• Analog display only
• Analog and digital displays
• Digital display only

Tachometer

The IPC displays the engine speed based on information received from the PCM. The PCM converts the data received from the engine into a 2 pulses per engine revolution signal. The IPC uses the engine speed signal circuit from the PCM in order to calculate the engine speed. The tachometer defaults to 0 RPM if a malfunction in the engine speed signal circuit exists.

Voltmeter

The IPC displays the system voltage as detected at the ignition 1 input of the IPC.

[Babydon]

Battery is brand new - AC Delco.

My head lights are after market HID's. I've had electrical issues before. Bad battery plus my headlights are wired to the positive charge under the hood.

This actually happened right after I changed a blown fuse for my headlights.

I think I'll drive her longer then check for codes again.

Thanks Mike!

[BodybyFisher]

Try disconnecting the battery maybe a surge or draw with your HID caused a problem in the IPC or PCM