2008 Town and Country Won't Read Normal Temperature What Is the Problem

Dan Ferrell writes about do-it-yourself auto maintenance and repair. He has certifications in automation and control technology.

Of course, the most common reason for an unusual reading on your automobile's temperature gauge is a problem with engine temperature. However, there are other reasons, for example:

• A bad temperature sending unit (the 2d most common reason)
• A problem in the temperature gauge'southward electric circuit
• A fault in the control excursion from the car'southward computer (depending on vehicle model)
• A bad temperature gauge

Whatsoever of these conditions may cause the temperature approximate to:

• read low
• read high
• go up and downwardly the scale

But your temperature approximate won't tell you lot which crusade you are dealing with. Unless you find some obvious symptoms under the hood or the trouble triggers the bank check engine light, you'll need to do a niggling diagnostic work to detect out what's going on.

The next sections describe the different ways your temperature approximate can give yous unusual readings, and the possible causes behind them. But first, let's have a cursory wait at how the temperature gauge works, and a few visible (and not so visible) symptoms that volition help you determine whether there's something wrong with your gauge.

Index
1. How a Temperature Gauge or Warning Light Works
ii. Is it the Temperature Gauge or Something Else?
3. Temperature Judge Reading Depression
four. Temperature Judge Reading High
5. Temperature Gauge Goes Up and Down
6. Checking the Temperature Sending Unit
7. Testing the Temperature Judge

1. How a Temperature Estimate or Warning Low-cal Works

Over the years the configuration of the automobile temperature guess has not inverse much. Its operating principles remain the same: A temperature sensor that reads engine temperature, and a brandish to evidence the temperature.

Thus, the temperature gauge on your dashboard is your window into the coolant temperature as seen by the temperature sending unit. It lets you know when the engine is cool, at operating temperature, overheating, or fluctuating.

The sending unit of measurement is a thermistor. Information technology is exposed on one side to engine coolant. Its variable resistance reacts to changes in coolant temperature:

• When the engine is absurd, as when the engine is off or has only been started, the sending unit's resistance is at its highest, preventing electrical current catamenia. The judge's indicator shows this by remaining at the depression terminate of the reading range.
• As engine coolant warms upwards, the sending unit's resistance decreases accordingly, and the gauge's indicator begins to rising. It'll remain at effectually the centre of the reading calibration, if the engine stays at operating temperature. A warning light won't come up on unless the engine overheats.

Until a few years ago, the temperature sending unit of measurement sent its information straight to the temperature gauge. Merely in most 1996 and newer models, the car computer is the interface between the approximate or warning light and the sending unit.

A faulty radiator fan may cause the temperature gauge to fluctuate.

Photo courtesy of Tony Harrison on Flickr.

Read More from AxleAddict

2. Finding Out if the Temperature Problem Is Your Engine or Your Guess

Unfortunately, when the temperature gauge reads too low, too high or fluctuates, you don't know whether something is wrong with the engine, the gauge, or something else. Unless the gauge is in the red zone and you lot meet steam coming out from nether the hood, of class.

Mostly, your temperature estimate will be accurate. But hither's a quick diagnostic that can help yous when you suspect something might be wrong with your gauge.

If possible, practise this initial inspection subsequently the engine has been running for more than twenty minutes, or as soon every bit your guess indicates an overheating condition.

Pop the hood open up and bank check the following:

• The coolant level should be at the Total Hot mark on the coolant reservoir tank. A low level will lead to engine overheating.

  • If your motorcar doesn't take a reservoir or recovery tank, expect for the engine to absurd and check the level through the radiator cervix. The level should be virtually 1/2 an inch below the bottom of the radiator cervix merely above the radiator cadre.
• Coolant should look dark-green or orangish. A rusty or cloudy color indicates contagion and may pb to overheating.
• The cooling fan should beginning running at approximately 230° F (110° C), which usually happens after xx minutes of engine operation. If the cooling fan doesn't plow on, it will pb to overheating.

• Compare the temperature of the engine head, near the thermostat, and the upper radiator hose. Both should experience hot to the bear on. The upper radiator hose connects the upper radiator tank to the engine at the thermostat housing.

  • If the hose feels cool or warm just the engine feels hot, either the thermostat is stuck closed, the radiator is clogged, or the water pump is not working. Any of these will lead to engine overheating.
  • If the hose and engine experience a bit warm just not hot, the thermostat is likely stuck open and will prevent the engine from reaching operating temperature. The gauge volition read below the regular temperature. Likewise, the heater might not produce enough rut.
• The lower radiator hose should feel a bit warm but non as hot as the upper hose. If both upper and lower radiator hose have nearly the same temperature, coolant is not circulating (overheating) or the thermostat is stuck open (engine below operating temperature).
• Look around for potential signs of leakage. Bank check radiator hoses, radiator, and h2o pump. If you run across coolant leaking, the system is running out of coolant and the engine is overheating.

Compare your findings to the gauge reading and decide whether the gauge reading is accurate.

If you demand more than help, this other post can help you find sources of engine overheating.

The following sections help you find potential problems behind a gauge that is reading low, high or fluctuating. Then y'all'll find a procedure to test both the sending unit of measurement and, if necessary, the temperature gauge.

A stuck-open up thermostat volition cause the temperature gauge to read low.

Photo courtesy of Hoikka1 on Wikimedia.

3. If the Temperature Gauge Reading Is Low

A temperature estimate that keeps reading low is non mutual unless there'due south a trouble with the cooling organization.

Potential problems include:

• A stuck-open thermostat
• Low coolant level (in a cold climate)
• Temperature judge disconnected from the temperature sending unit
• Bad temperature sending unit of measurement
• Faulty estimate
• Excursion problems in the gauge or sending unit (loose or corroded connectors).
• Car calculator issues, if the calculator works as an interface

A clogged radiator is hard to diagnose since y'all tin't meet coolant flow brake.

Photo courtesy of Gwydion 1000. Williams on Flickr.

4. If the Temperature Gauge Is Reading High

A temperature gauge will normally rise above the center range when driving in heavy traffic, carrying or pulling a heavy load, or going up a steep hill. However, if the gauge approaches the college (hot) end of the scale nether normal driving conditions, it unremarkably points to problems with the cooling organization.

Other potential causes include:

• Low coolant level

  • Check both reservoir tank and radiator.
  • Check for leaks, including the radiator, water pump, heater core, hoses, and cylinder head gasket, every bit necessary.
  • In some cases this may lead to detonation (a banging audio)

• Loose radiator cap or faulty seals

  • Visually bank check radiator neck and cap for damage, and exam cap pressure, if necessary.
• Coolant not flowing, due to a clogged radiator, partially open or stuck-closed thermostat, or a bad water pump
• A faulty cooling fan
• A radiator front blocked with bugs and debris
• Bad coolant mixture
• Bad temperature gauge

A failed impeller in a h2o pump volition prevent coolant flow and cause overheating.

Photo courtesy of Razor512 on Flickr.

5. If the Temperature Guess Goes Up and Downwards

Y'all may find that your temperature gauge reading goes upward and down, fluctuates in some kind of pattern, or is erratic.

In that location may be several reasons for this:

• Low coolant level delaying thermostat opening and closing (check coolant level in the radiator).
• Air pockets in the cooling organisation
• A coolant leak
• A partially clogged radiator
• A water pump with a loose impeller
• A loose bulldoze chugalug failing to operate the water pump properly
• A short, or loose or corroded connectors or wires, in the the electrical circuit for the sending unit or guess
• Cooling fan or relay bug
• Faulty thermostat
• Bad temperature approximate
• Blown caput gasket with exhaust gases messing up thermostat performance

Forestall Computer Damage!

If your car figurer acts as an interface betwixt the sending unit of measurement and temperature gauge or warning lite, turn the ignition switch off when disconnecting wires from the sending unit, warning light, or temperature gauge. You demand to practice this to prevent induced-voltage damage to the computer. Consult your vehicle repair manual.

When you suspect a bad temperature gauge, most likely the temperature sending unit is the culprit.

Photo courtesy of Sfoskett~commonswiki on Wikimedia.

6. Checking the Temperature Sending Unit of measurement

When you suspect that something is wrong with the temperature gauge, you desire to outset cheque the temperature sending unit of measurement, which is more accessible and more prone to failing.

You can examination the sending unit of measurement's resistance or voltage using a digital multimeter (DMM).

Older vehicle models utilise a unmarried temperature sending unit of measurement connecting to the temperature gauge. Newer vehicle models connect to the electronic command unit (ECU) or motorcar computer, which then sends information to the temperature approximate. Other vehicle models, peculiarly Asian models, use two temperature sending units, one continued to the computer and the other one to the temperature approximate.

You may demand to consult the vehicle repair manual for your particular model to locate components, identify wires and terminal connections. If you don't have the repair manual, you can buy a relatively inexpensive re-create from Amazon. Haynes manuals come with pace-by-step procedures for many troubleshooting, repair and component replacement projects yous can do at home.

Testing a sending unit of measurement's resistance:

1. Locate the temperature sending unit. Usually the unit of measurement is located close to the thermostat housing, which connects to the upper radiator hose on the engine cylinder head.
2. Unplug the sending unit electrical connector.
3. Measure the unit's resistance when the engine is cold using an ohmmeter. Resistance should exist high.
4. Measure the unit'southward resistance when the engine is hot. Resistance should exist depression.
5. Compare your readings to specifications in your vehicle repair transmission. If the sending unit specifications are correct, continue with the next steps.

Testing for reference voltage:

1. Turn the ignition switch off.
2. Unplug the wiring harness from the temperature sending unit.
3. Connect your voltmeter's red lead to the reference signal wire metal terminal.
4. Connect your voltmeter's black lead to the battery's negative (-) mail.
5. Plough the ignition switch to the On position, but don't beginning the engine.

You should take a 5 or 12 volts reference signal. If non, check that wire for damage. If the wire is coming from the computer, and the wire seems in practiced condition, the computer may be bad. Consult your vehicle repair transmission.

Testing a sending unit'southward output voltage:

On some models, you'll exist able to dorsum-probe the sending unit'due south signal wire using your voltmeter.

1. Connect the meter'south red lead to the sending unit of measurement's signal wire (consult your repair manual, if necessary).
2. Connect the meter'southward black lead to engine footing or the battery negative (-) mail.
3. With the engine common cold, engage the parking restriction, start the engine, and let it idle.
4. Observe the voltage readings as the engine warms up. Your readings may be similar to the values in the next table, with a reference voltage of v volts to the sending unit from the computer (some models may apply a reference of 12 volts).

Temperature	Voltage
110F (43.3 C)	4.2
140F (60 C)	three.half dozen
180F (82.2 C)	2.viii
210F (98.8 C)	2.two
230F (110 C)	ane.viii
250F (121 C)	ane.4

A bad temperature sending unit tin can also cause a motorcar's estimator to make fuel arrangement adjustments based on incorrect data. You may see, for example:

• Black exhaust fume
• Hard starting on a warmed engine
• Increase in emissions

The following video gives you some visual clues about testing the sending unit.

vii. Testing the Temperature Gauge

If the sending unit tested okay, and y'all doubtable a bad temperature gauge, you tin use this general procedure. Yous may need to consult your vehicle repair manual to place or locate wires and components.

Note: The process below requires grounding the wire that connects to the temperature sending unit. On some models, grounding this wire can harm the temperature gauge. If necessary, consult your vehicle repair manual to find out if your car has this issue.

Note: If your machine computer controls your temperature gauge or warning calorie-free, follow the next three suggestions before proceeding with further troubleshooting steps:

1. If the check engine light is on, check for diagnostic trouble codes (DTC) first. The codes may point to the source of the problem, normally a sensor or circuit issue.
2. Brand sure to turn the ignition switch Off before unplugging wires.
3. Then plough the ignition switch On to check judge or warning light response as indicated in the post-obit steps. This will forbid damage to the computer.

Continue Troubleshooting

1. Turn the ignition switch Off.
2. Unplug the sending unit electrical connector and plow the ignition switch On. Whether the engine is warmed upwards or absurd, the gauge should read cold.

3. Basis the sending unit (signal) wire using a jumper wire. Turn the ignition switch On. The gauge should read "hot" or the alarm low-cal should come on.

   • If the temperature gauge responds every bit described, but not when connected to the sending unit, the sending unit is bad.
   • If the gauge reads higher than "cold" when you unplugged the sending unit of measurement, unplugged the wire at the temperature estimate. If the gauge now reads "cold," the wire is shorted. If the gauge notwithstanding reads higher than "cold," supplant the gauge.

   • If the guess doesn't read "hot" when the wire is grounded, check the excursion fuse. If it is okay, ground the gauge terminal where the wire connects to.

     • If the gauge at present reads "hot," check the wire for harm.
     • If the judge still doesn't read "hot," make certain there's voltage at the ignition last of the gauge. Follow the next procedure:
     • Using a test light, connect its wire to basis and the probe to the estimate'south positive terminal. If the test lite glows with the ignition turned on, supersede the gauge; otherwise, apply a jumper wire betwixt the ignition switch and the judge's positive terminal. If at present the guess works as described above when unplugging and grounding the point wire, then check the wire betwixt the ignition and gauge; otherwise, supercede the judge.

On some newer vehicle models, getting access to a temperature gauge on the musical instrument cluster may be difficult. Sometimes, using a scan tool is the best choice to troubleshoot this blazon of problem. Furthermore, on some models a bad temperature gauge requires either calibrating the musical instrument cluster or installing a new cluster. Consult your vehicle repair manual.

On modern vehicles, you may utilise a scanner tool to test the sending unit and temperature guess.

Photograph in the Public Domain.

If you have determined that the temperature gauge has failed, you may desire to check for a possible recall on your vehicle model on this particular issue.

A temperature estimate, or even an instrument cluster, may come out of the manufacturing plant with problems that may not manifest themselves subsequently miles of operation.

You lot tin cheque for a recall on your vehicle online, your local dealer or car repair store.

This content is accurate and truthful to the best of the author's cognition and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers

Question: Which fuse is the temp guess?

Answer: You might have a fused wire going to the instrument cluster if you don't take a divide guess. Look under the lid for the fuse box.

Question: I am the owner of a Honda CRV Rd1. The temperature estimate reads high while driving over 60km/h and my AC unit stopped cooling. I pulled over and checked that both fans were on and the radiator and hoses didn't experience out of the ordinary. I even checked the overflow fluid and the h2o was absurd plenty to be touched. I'm totally confused. Whatsoever ideas or suggestions?

Answer: There are some common issues that ordinarily can be traced to this trouble (only non the just ones): first, make sure the water pump is working properly. See if you tin can hear whatever noises (worn bearing) coming from the water pump. Second, a clogging radiator condenser (plugged fins-perchance); third, issues with a faulty Air conditioning compressor.

Question: I have a 2005 Pontiac Grand Prix and the temperature gauge isn't working. I've replaced the battery, h2o pump, thermostat, and I've had the computer reset. What is my problem now?

Respond: Check the gauge circuits, sometimes information technology'south a only a elementary faulty ground or the gauge itself that is bad. Get over the tests in the post. That should assist to narrow down or find the issue.

Question: What does it mean when my motorcar's gauge registers only when the ignition is off?

Answer: Check the temperature sending unit and, if necessary, its excursion.

© 2019 Dan Ferrell

okanesaingestur.blogspot.com

Source: https://axleaddict.com/auto-repair/Why-is-My-Car-Temperature-Gauge-Not-Working

Share this post