Chery A18. Manual — part 21

Diagnostic trouble code: P0647 “Overvoltage in control circuit of A/C
compressor relay”

Item

No.

Operation procedure

Inspection

results

Follow-up

procedure

1

Connect the diagnostic tester and adaptor
and turn the ignition switch to “OFF”
position.

Proceed to next step

Yes

Proceed to Step 4

2

Pull out the A/C relay, turn the ignition
switch to “ON” position and check if the
voltage between the power supply
terminal of relay (i.e. 30# and 85# pins of
the relay) and the negative grid of power
supply is about 12V.

No

Proceed to next

step.

Yes

Repair or replace

the wiring harness

3

Check if the power supply circuit of relay
is open or short to ground.

No

Proceed to Step 2

Yes

Replace the relay

4

Inspect with multimeter to check if the
voltage between the control terminal of
A/C compressor relay (i.e. 86# pin of the
relay) and the negative grid of power
supply is about 3.7V.

No

Proceed to next step

Yes

Repair or replace

the wiring harness

5

Check if the circuit between the control
terminal of A/C compressor relay (i.e.
86# pin of the relay) and 70# pin of ECU
is short to supply.

No

Refer to diagnosis

help

Diagnostic trouble code: P1651 “Malfunction in control circuit of malfunction

alarm light”

Item

No.

Operation procedure

Inspection

results

Follow-up procedure

1

Connect diagnostic tester and adaptor,
and turn the ignition switch to “ON”
position.

Proceed to next step

Yes

Proceed to next step

2

Check the action of engine malfunction
alarm light by using the “actuator
action testing" function of diagnostic
tester and observe whether the light is
always on or off.

No

Normal operation

Yes

Repair or replace the

wiring harness.

3

Verify that the supply circuit of engine
malfunction alarm light is open or short
to ground.

No

Proceed to next step

Yes

Repair or replace the

wiring harness.

4

Check if the supply circuit between the
control

terminal

pin

of

engine

malfunction alarm light and 29# pin of
ECU is open, or is short to ground or
power supply.

No

Refer to diagnosis

help.

PROCEDURES FOR FAULT DIAGNOSIS ACCORDING TO THE

SYMPTOMS OF THE ENGINE

A preliminary inspection should be carried out before implementing the steps of fault
diagnosis according to the symptoms of engine:

(1) Verify that there is no abnormal behavior with the ECU and malfunction indicator

light (not applicable for car models without setting of malfunction indicator light).

(2) Inspect with the diagnostic tester or flashing light to verify that there is no

malfunction information record.

(3) Inspect the idle speed data of warmed up engine in the electronic control system

with the diagnostic tester and verify that they are normal.

(4) Verify that the malfunction symptom complained by the car owner exists and

locate the exact position of the symptom.

Then carry out the visual inspection: Verify that the grounding point of the wiring
harness is clean and firm.

Verify that the vacuum pipelines have any ruptures or twists together, and whether its
connections are correct.

Verify that the pipeline has any symptom of blockage.

Verify that the air inlet pipeline is flattened or damaged.

Verify that the sealing between the throttle body and the air intake manifold is in a
good condition.

Verify that the high voltage cable of ignition system has any rupture or ageing, and
whether the wire routing is correct.

Verify that the connection of conducting wire is correct and whether the connector is
loose or poorly contacted.

1) The engine is not running or running slowly during starting

Item

Operation procedure

Inspection

results

Follow-up procedure

Yes

Proceed to next step

1

Inspect with multimeter to see whether there
is a voltage of about 10-12.5V between two
battery terminals.

No

Repair or replace the

battery

Yes

Proceed to next step.

2

Turn the ignition switch to “ON” position.
Inspect with multimeter to see whether there
is a voltage of about 10-12.5V between the
terminals connecting the ignition switch and
the positive grid of the battery.

No

Repair the terminal

or replace the

conducting wire

Yes

Proceed to next step.

3

Keep the ignition switch at the startup
position and inspect with multimeter to see
whether that there is a voltage of more than
8V between the terminals connecting the
ignition switch and the starting motor
magnetic clutch.

No

Repair or replace the

ignition switch

Yes

Repair or replace the

starting motor

4

Inspect with multimeter to see whether the
starting motor has any open or short-circuit.

No

Proceed to next step.

Yes

Fix the malfunction

5

Verify that the engine is jammed due to
poor lubricating.

No

Proceed to next step.

Yes

Replace with

appropriate

lubricating oil

6

In case of winter season, inspect to see
whether there is too much friction in the
starting motor due to the improper selection
of engine lubricating oil and gearbox oil.

No

Inspect other items