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737. Unstable idle or engine shut off at hot status
(1) Symptom
Idle speed is normal during the cold start and becomes unstable at hot status, idle speed is too
low or engine is shut off.
(2) Causes and Troubleshooting
a. Idle is adjusted too low, adjust it to normal condition;
b. Water temperature sensor fault, repair or replace it;
c. Poor injector operation or big injection variation, repair or replace it;
d. Poor water temperature switch and thermostat operation, repair or replace it;
e. Check valve is damaged and needs to be replaced.
Figure 152Rough ildling, easy for engine shut off
Check whethe the air tightness of the intake system is good Poor
Troubleshooting
OK
Check idle control valve for operation Inoperative
Disassemble or replace
Operative
Reset the initial idle speed
Check the spark plug Poor
Adjust the clearance or replace
OK
Check the fuel pressure NG
Check the electric pump, fuel
pressure regulator and fuel filter
OK
Check the injector NG
Replace
OK
Check the pressure sensor NG
Replace
OK
Check the cylinder compression pressure NG
Disassemble the engine
OK
Check and adjust the valve clearance
Page 245 of 392
238Section 4 Audio and Video System ReplacementI. Notice on operationPlease explain to the customer that the AM/FM broadcast channel information will be cleared when remov-
ing the battery negative terminal cable. Record the channel information before removing the negative termi-
nal cable if necessary. Reset after connecting the negative terminal cable.
yAll cassette tapes and CDs must be taken out before radio removal and installation.
yIf the cassette tapes and CDs can not be taken out due to radio fault. Do not take them out by force.
Drive the vehicle to Service Station.
yMake sure the grounding bolts are tightened before antenna removal and installation.
yThere will be noise when receiving electric wave if the grounding bolts are not tightened.
yDon't touch the speaker cone.Intermediate Multiple CD main unit Radio assemblyInstrument PanelMultiple DVD main unit
Page 255 of 392

248An external watchdog can check the operation situation of the microcontroller. The failure of the microcontroller
can trigger the watchdog, which in turn can reset the microcontroller and turn on the warning light.No. List of Trouble s Trouble De sc ription
1 M ic r oc ont r olle r z AD c onve rte r or EEP ROM trouble (in
case of RAM and ROM failure, the
mic r oc ont r olle r w ill r e s e t a nd t he w a r ning
light will light up.) z Activate trouble z
Che ck the circ uit trouble z Activate trouble z Check the circuit trouble z Activate trouble z Chec k the c irc uit trouble z Activate trouble z Chec k the c irc uit trouble z Activate trouble z Check the circuit trouble z Activate trouble z Check the circuit trouble
6 Ignition volta ge z Low
7 Wa tchdog/rese t z Trouble
8 Maximum times of e xplosion of the se a t belt
pretensioner z 6
9 Ene rgy stora ge time (self-support time ) z Short z Ra nge of de via tion z Se nsor not in ste ady mode z Se nsor se lfc hec k trouble
11 Continuous abortion of ignition circ uit che c k z None xec ution of c irc ula r diagnostic test
(Repeated algorithm calculation) z Close for 2 or more tha n 2 sec onds z Sa fe ty se nsor is open c irc uit when
calculating the trouble with algorithm
13 Ignition c urre nt z All the ignition currents are normal
when the current SRS is deployed
14 No c onfirma tion of side SRS ignition z Eve n if the SRS ECU (HAE2.5) ha ve
received for 5 times the ignition information
during the HSIS ignition cyc le, the side SRS
a irba g ignition c a n not be ve rifie d by SRS
ECU (HAE2.5). Seat belt pretensioner ignition circuit (if realized)
5 P asse nger se a t be lt pre tensione r ignition c irc uit
(if realized) 2 P asse nger airba g ignition c ircuit
3 P asse nger airba g ignition c ircuit (if re a lize d)[Ta ble ] Inte rna l troubles pre dic te d by SRS ECU (HAE2.5)
10 Accelerometer
12 Sa fe ty se nsor6 Driver airbag ignition circuit (if realized)
7 P asse nger airba g ignition c ircuit (if re a lize d) 4
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250(2) Trouble indication
1In case of a trouble, the warning light will indicate. If the external trouble is a history trouble, the indication
will be cancelled. When the history trouble happens for no less than 5 times, the indicator light will remain
on even if there is no more trouble. "Low battery voltage" shall not be counted in the total number of
troubles.
2Only a service worker can reset a displayed or history trouble. The internal troubles of a SRS ECU
(HAE2.5) or the "crash record" of a trouble cannot be reset, in which case the SRS ECU (HAE2.5) shall
be replaced.
(3) Microcontroller-independent warning light on
Microcontroller with definitive troubles cannot fulfill its functions, thus cannot control the warning light. In
this case, the warning light will light up through proper circuit regardless of the microcontroller as stated
below:
yMalfunction of the battery supplying power to SRS ECU (HAE2.5): the warning lights are turned
on continuously by means of the drive function of the selfcheck light.
yLoss of internal working voltage: the warning light remains on.
yReset due to trigger failure of the watchdog: the warning light blinks.
yMicrocontroller out of work: the warning light always lights up.
yIncomplete insertion of SRS ECU (HAE2.5) connector: the warning light remains on by means of
a shorting bar.
The diagnostic procedures can well be illustrated as follows:
If it is found that the SRS warning light remains on, follow the undermentioned procedures to check even if
the light goes out eventually. First, a scan meter is used to check the location of the trouble.
Then£¬go on with the checking in accordance with specific methods and procedures for the correspondent
location.
a. If the result indicates that it is an internal trouble or that the SRS is already detonated, replace the
ECU directly.
b. Troubleshooting.