I have a 1996 GMC Suburban. The past week or two temperature gage seems to be malfunctioning. After only about 5 minutes of driving the temp gage will shoot up and then shoot back down. It will shoot up to the red zone, stay there for a minute or so and then rocket back down to below normal. Even though the gage shoots into the red zone, the truck never over heats. Never hear any hissing, never see steam and seems to perform just fine. We used to pull over when it got to the red zone but now we just drive through it because it always comes back down without incident.
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diognostics say its a sensor ?????? No diagnostic's ever tell's you it's a sensor . You as a technician would need to prove that by testing electrical circuits , viewing coolant temp sensor . Hooking scan tool and trying to command the gauge with by directional control . The temp gauge not showing any temp. ? No movement ?
Engine Coolant Temperature Gage Inaccurate or InoperativeStep
Schematic Reference: Instrument Cluster Schematics
Did you perform the Instrument Cluster Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - Instrument Cluster
Install a scan tool.
Turn the ignition ON, with the engine OFF.
With the scan tool, perform the Lamp and Gauge Check in the IPC Special Functions list.
Does the engine coolant temperature gage move up and down when commanded?
Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
Go to Step 3
Replace the IPC. Refer to Instrument Cluster Replacement .
Did you complete the replacement?
Go to Step 4
Operate the system in order to verify the repair.
Did you correct the condition?
Go to Step 2
Would hate for you to replace the coolant temp sensor an find out that's not the problem ! Does the vehicle start an run good ,trans mission shift good ? If so it's not the coolant temp sensor .
Engine Coolant Temperature Gage
The ECM sends coolant temperature as determined by the coolant temperature sensor to the BCM via CAN serial data. The IPC displays the engine coolant temperature with the gage when the BCM sends a class 2 message to the IPC indicating coolant temperature percentage. The engine coolant temperature gage defaults to cold (0°) or below if:
• The ECM detects a malfunction in the engine coolant temperature sensor circuit.
• The IPC detects a loss of class 2 communications with the BCM.
• The BCM detects a loss of CAN communications with the ECM.
code p 0480 refers to engine coolant blower motor 1 ---circuit malfunction=== causes ---wiring ---engine coolant blower motor ---ECM
code p 0116 refers to engine coolant temperature (ECT) sensor ---range b/performance problem ====causes coolant thermostat---poor connections---wiring---ECT sensor
Hi Julia , why do you believe you need to find the temp sensor ? Temp gauge not working ? The cooling Temp sensor is a input to the PCM / ECM - engine computer .
Engine Coolant Temperature Gage
The instrument panel cluster (IPC) displays the engine coolant temperature (ECT) as determined by the powertrain control module (PCM) or the powertrain control module (PCM). The IPC receives a class 2 message from the PCM indicating the ECT. The range on the ECT gage is between 60-125°C (140-260°F). The ECT gage defaults to 60°C (140°F) or below if the PCM detects a malfunction in the ECT sensor circuit. Refer to Cooling System Description and Operation .
Would have DTC- diagnostic trouble code stored in Instrument cluster or the check engine light would be on . Before replacing a part you may not need take it to a qualified repair shop to have it diagnosed .
CHECK GAGES light (1) indicates a potential engine failure(low oil pressure, low coolant, coolant overheating) has occurred. · Check gages and shut down engine. Gages should read as follows: Oil pressure 5 to 10 psi (34 to 69 kPa) at idle; Water Temp gage below 230 degrees (110 C).
· Check engine oil level (Para 2-11) if OIL PRESS gage indicates low reading. Check coolant level (Para 2-11) if Water Temp gage indicates high reading. Notify Unit Maintenance if levels are low.
If CHECK ENGINE light (2) is on, check engine oil pressure gage (3) and water temperature gage (4). If both indicate normal, proceed with mission and then notify Unit Maintenance. If either one does not indicate normal, stop engine immediately and notify Unit Maintenance
located the temp sending unit check that its pluged in, if it is unplug it and ground the wire to something metal (with the switch on) and see if the gauge moves if it does then your temp sending unit is bad and needs replaced
Is it just the gauge or is the engine coolant temperature varying? Does the heater seem to vary in temperature when it is on. It could be a couple of different things. One could be a malfunctioning temp sending unit, it has lost its calibration. Two, your thermostat is cycling open and closed from a weak return spring, worn out. Make sure coolant level is correct and the mixture is 50/50. Let me know. Regards,
engine coolant temp. sensor is probly cracked it will cause the idle to race, car may smoke, and at time could be hard to start.. It is about 15 dollars, and it is located on the right side of the head if you are looking at the engine.. pull it out you will be able to see if the tip of the ceramic tip is cracked.