Question about 1999 Land Rover Discovery

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1999 discovery is overheating, cooling fans are not coming

Disco is overheating, cooling fans are not coming on when air conditioner is turned on. relays and fuses are o.k. Cannot find the fan control module. the mechanics guide picture looks like its pointing to the emissions reminder box. There is another relay thats white in color and covered in rubber I havn't been able to identify yet. all relays and fan control appear to be on the right hand side under the dash or right. Any ideas?

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  • terrys919 May 11, 2010

    Thermal Switch? I have the same problem on my 98 Disco 1. I have replaced the fans and still nothing. I am getting power to the fans when the AC is turned on but the fans do not turn. Are the fan motors bad if power is there at the fan motor but no activity? Or is there something else to check? Thanks.

  • hector 1219 Sep 14, 2013

    you dont have a picture of the thermal switch???

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This is because of the improper circulation of the coolant, if the AC turned on then the engine load will be considerably increase and spoil the thermal switch (which initiate the cooling fan to run). So you better clean the radiator and check the radiator pump, then replace the thermal switch to get the things done.

Posted on Jul 23, 2009

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2009 chevy hhr speakers don't work and a/c radiator fan won't come on


What engine does it have ?

Cooling Fan Control 2.0L
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the engine cooling fan motor in relation to the PWM signal. The cooling fan speed can be adjusted from 10 percent to 94 percent duty cycle. 94 percent is considered high speed fan.
Cooling Fan Control 2.2L or 2.4L
The engine cooling fan system consists of one cooling fan and one relay. Voltage is supplied to the relay through a fuse. The engine control module (ECM) controls the fan operation by grounding the cool fan relay control circuit. When the cool fan relay is energized, voltage is delivered to the cooling fan motor. The cooling fan motor is grounded through its own ground circuit.
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent the fan from cycling ON and OFF excessively at idle.


Just one speaker doesn't work ? Do you know how to do automotive electrical testing ? That's how to find both your problems . Speakes work by electrical inpluse's . The A/C radiator ( condenser ) fan also works by B+ voltage through a fuse an a relay , controlled by the engine electronic control module or PCM - powertrain control module . When you push the A/C turn on button , it sends a signal to the PCM . The PCM will then energize the radiator fan relay turning on the fan . Check fuse in the under hood fuse box , If the fuse is blown you have a electrical short , too much current flow . Plus if the PCM sees too much pressure in the A/C system it will not let the A/C work .

Mar 31, 2017 | Cars & Trucks

2 Answers

FANS WONT COME ON ,,ALL FUSES,RELAYS AND ELECTRIC FAN MOTORS ARE NEW,,THERMOSTAT IS GOOD,,WHERE IS ELECTRIC FAN TEMP SENSOR LOCATION


op
why not post symptoms first and not a barrage of parts.
must we decode that to a symptom,. kinda hard right.

I will not guess. what is wrong, nor what is not working on your car. now what fans you are talking about, up to 4 fans on cars.

cab blower fan (wild guess blower is ok) and so is HVAC, ?
radiator fans
Condenser fan.

my wild guess to , engine over heats?????????
if yes, the scan it first. no not last FIRST.
it dont work like you think its not a 1988 Samurai.
sorry,
on modern cars, they got smarter, the engine goes
gee the PCM knows water temp why have a fan temp regulator.
hark , now it dont. (saves cash on useless parts)
but has a relay , (well until you have my car and the relay is now 100% electronic, called a huge transistor)
we've used this tech in industry for years, but car makers just learning how still.
i digress. but evolution and history helps diagnosis.
what is there?

Ill look for you, ive posted this 100s of times
the book is 4 bucks to see online. the real deal
lets look now.
XL-7 (the dash matters big time)
answering for , overheats engine, and fans on RAD dead.
(some are staged, PCM brains... now. and also chain ops based on if A/C is on or not) facts.
first I see 2 fans... ok.
the next page shows nice block diagram of the fan system
yup, NOT Simple.

ill post those words for you.
"The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans receive positive voltage from the cooling fan relays which receive battery positive voltage from the underhood fuse block.
During low speed operation, the ECM supplies the ground path for the low speed cooling fan relay which is fan 1 relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the fan 1 fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the series/parallel relay which is fan 2 relay, and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. The ECM grounds the high speed fan relay, which is fan 3 relay, and the series/parallel relay, which is fan 2 relay through the high speed cooling fan relay control circuit. This energizes the series/parallel relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the fan 2 fuse 1 on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 16 km/h (10 mph). This is to prevent a fan from cycling ON and OFF excessively at idle.
end quote.

i bet you didnt scan it , like 99.9 % of all posters here dont.
DTC Descriptors
DTC P0480: Cooling Fan Relay 1 Control Circuit
DTC P0481: Cooling Fan Relay 2 Control Circuit
DTC P0691: Cooling Fan Relay 1 Control Circuit Low Voltage
DTC P0692: Cooling Fan Relay 1 Control Circuit High Voltage
DTC P0693: Cooling Fan Relay 2 Control Circuit Low Voltage
DTC P0694: Cooling Fan Relay 2 Control Circuit High Voltage
Diagnostic Fault Information

is the ECT showing overheat, yes no?
if yes, it must operate a fan or 2.
the book even covers all tests for fans dead, in a large truth table.
both the FSM and alldata.com have that, its no secret ,its published in 4 major places.

lets back up
if the engine coolant is low (no that side tank the engine and rad)
the ECT will lie. if that happens the fans may not come one
that is because the ECT is useless measuring air, for water.
that water must touch ECT for ECT to work.
this is FIRST
then scan the ECT does it show overheating, IT must if it IS overheating. fix that next if it lies to you,(IR gun in hand)

The system has staged fans.
i cant find the trip points in my crappyy online pages.
but is like 225f then 250f trips. is my guess...
about. if the engine over heats, check fuses first then scan it.
it will simply tell you why its bad.
eg, fan1 output dead.
or if you hot wire a fan and its dead, then it is.
(only on cars with non modulated fans,,hot wire them,else not.)

now the link to the 4 buck real book.
the non dash XL7 (my guess) you this pick yourself... cant see car.
https://suzukipitstopplus.com/Products/10182-2007-xl7-service-manual.aspx

this is how it really works
the ECU has software that decide trip points for fans.
hard coded, this is. based on how hot it is and if A/C is on not.
its way smarter than 1988 and better.
the DTC errors can see an open line, shorted to ground or stuck 12v.(runs all time error)
(tells you relay is good or not)

25839272-0kjd5huq4lpr130nt243wle5-3-0.jpg no scanner no joy , sorry, tis a fact.....

25839272-0kjd5huq4lpr130nt243wle5-3-2.jpg

Aug 27, 2015 | 2007 Suzuki XL-7

1 Answer

Cooling fan does not run?


At the main fuse and relay box, check the 30A EGI INJ fuse. If OK, the main relay closes to apply power to the cooling fan relay. Next, check the 30A FAN 1 and FAN 2 fuses.If OK, power is being applied to the fan control module. The PCM processes engine coolant temperature sensor input and sends a signal to the fan control module which, in turn, causes the cooling fan motor to operate. Fan failure could be caused by malfunction of the cooling fan relay, the fan control module, the engine coolant temperature sensor, the cooling fan motor itself, or the PCM

Oct 06, 2012 | 2005 Mazda MPV

1 Answer

Code P0481


Both radiator fan relay's ????? There are three relay's !
DTC P0481Cooling Fan Relay 2 Control Circuit
Circuit Description
Output Driver Modules (ODMs) are used by the PCM to turn on many of the current-driven devices that are needed to control various engine and Transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding on. DTC P0481set indicates an improper voltage level has been detected, which controls the Cool Fan 2 and Cool Fan 3 Relays.

Check cooling fan maxifuse 15 amp. This fuse supply's B+ voltage too cool fan relay's 2 & 3 control side . The PCM supply's a ground to energize these two relay's , the PCM is not seeing the correct voltage that it should be . The fuse could be the problem , an open circuit , the transistor or driver as GM calls it output driver module . The number 1 relay is working fine , with A/C on # 1 relay is turned on or energized by the PCM for low speed operation .
There is a good video on youtube on how this three relay cooling fan system works an how to trouble shoot .
Relay Driven Dual Cooling Fan Diagnostics

Nov 03, 2017 | 1999 Buick Century

3 Answers

Ford focus 2006 engine overheating once ac swicth is on..


CHECK TO SEE IF COOLING FAN IS RUNNING.IF NO CHECK COOLING FAN FUSE AND RELAY.THE COOLING FAN NEED TO BE RUNNING WHEN AC ON BECAUSE AIR CONDITIONER PUT A LOAD ON ENGINE.COOLING FAN KEEP RADIATOR AND AC CONDENSOR COOL.FAN NEED TO RUNNING.

Sep 04, 2011 | Ford Focus Cars & Trucks

2 Answers

Overheats if left idling but not if driving...cooling fans aren't coming on...what couls be wrong?


the cooling fans on your car are comanded on by the engine control module which reads engine temperature from the temperature sensor . when comanded on the engine control module sends a signal to the cooling fan relays . which in turn runs the current to the cooling fans . So you might want to check the cooling fan relays and make sure the fues for the cooling fans are good and the relays .if the cooling fan fuses and relays are good it could be a problem with the fan motors or the engine control module not reading the right temperature in that case it could mean you have a problem with the temperature sensor

Mar 04, 2011 | 1998 Cadillac DeVille

3 Answers

COOLING FAN WONT KICK ON. DID A JUMP TO THE BATTERY FROM THE OUTSIDE PLUG AND FAN KICKED ON. BOUGHT A NEW RELAY FOR UNDER THE DASH BUT FAN STILL WONT COME ON. IS THERE A FUSE TO?


The cooling fan relay is located in the engine compartment just behing the left headlamp...not under the dash. There are cooling fan test connectors built into the wiring harness near the left strut tower. The cooling fan relay is controlled by the cooling fan temperature switch located on the rear of the engine. There are 3 temperature sending units on your car if it is equipped with a temperature gauge. If not, there are 2 sending units, One is for the computer and the other is for the fan relay.

The one for the cooling fan will have 2 wires, one Tan and Orange and the other Brown and White.

The cooling fans and cooling fan relay get their power from fusible links built into the wiring harness near the starter relay.

Dec 19, 2010 | 1991 Ford Tempo 4 Door

2 Answers

I just changed my radiator,thermostate.But it is still overheating.I don't see any smokes,but the gauge for the temperature above normal.What should I do?


The radiator fan may not be blowing.
Idle car with parking brake engaged.
Turn OFF Air Conditioner
Pop open hood and look at the radiator fan.
It is not spinning.
Turn ON Air Conditioner and look at fan.
The fan MUST be spinning.

Replace the "Radiator fan" relay switch.
Check primary fuses and replace as needed.

Nov 09, 2009 | 1998 Subaru Forester

2 Answers

In our 1995 Cadillac Deville we can't get the fans to come on to cool the radiator. There are four relay switches and we don't know if we have to replace all of them or is there just one and where is the...


The most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.The hose goes in to the engine to a crossover and comes out the other side to near the thermostat housing,the blockage may be there.

Oct 28, 2009 | 1995 Cadillac DeVille

1 Answer

Radiator fan


You should check the 30 amp "RDI" fuse and the 7.5 ECU-IG fuse. Both fuses are critical to the operation of the fan system. The RDI fuse sends power to the fan #1 relay. The A/C amplifier turns on power to the fan #1 relay, this is why your fan works on A/C.

Now, with no cooling fan under "normal conditions" (A/C off), you need to have a good fan #2 relay, and a good water temp switch. This switch is on the engine, near the thermostat housing (I think); with a single plug, with a white with a blue trace wire going to it. Remove this wire from the sender, and jump it to ground (anywhere on the metal of the engine) with the key on (engine OFF). If the fan starts, you need a new water temp sending unit. If not, then consider a new fan #2 relay. This system is pretty simple.

Sep 24, 2008 | 2002 Toyota ECHO

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