Page 69 of 94
ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of statuses87G
87G-69V7 MR-372-J84-87G050$550.mif
UPC
Vdiag No.: 48, 4C
ET023
ALTERNATOR THERMAL FAULT
NOTESSpecial notes:
Apply the checks if the status is PRESENT with the engine running.
Switch off the engine.
Check the general condition of the alternator:
Make sure that there are no foreign bodies that could impair the alternator cooling.
Clean the alternator if necessary.
With the engine stopped, let the alternator cool down with the bonnet open for at least 1 hour.
Start the engine with the bonnet closed.
Switch on the main beam headlights and the electrical heated rear screen.
If the status becomes PRESENT again, replace the alternator (see MR 364 or MR 370 Mechanical, 16A,
Starting - Charging, Alternator: Removal - Refitting).
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_ET023 /USM_V4C_ET023
Page 71 of 94
ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Parameter summary table87G
87G - 71V7 MR-372-J84-87G050$605.mif
UPC
Vdiag No.: 48, 4CENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Parameter summary table
Tool parameter Diagnostic tool title
PR004Battery voltage
PR008Battery voltage after rest
PR010Alternator charge
MR-372-J84-87G050$605.mif
Page 74 of 94

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of parameters87G
87G-74V7 MR-372-J84-87G050$660.mif
UPC
Vdiag No.: 48, 4C
PR010
ALTERNATOR CHARGE
NOTESIf fault DF007 UPC-alternator connection is declared present, deal with this fault first.
Start the engine and let it idle for 5 minutes.
Check that the fan units are not running.
Without any electrical consumers switched on, check the value of PR010 Alternator charge.
PR010 decreases and is < 50 % after a few minutes.
"YES"
No interfering consumer is disturbing vehicle operation.
–Switch on the electric heated rear screen and the main beam headlights.
–Wait 20 seconds and then check that PR010 Alternator charge has increased but
remains less than 90%.
If PR010 Alternator charge remains stuck at 99.6%, replace the alternator (see MR 364
or MR 370 Mechanical, 16A, Starting - Charging, Alternator: Removal - Refitting).
PR010 remains > 50% after 20 minutes.
–See 16A, Starting - Charging, Alternator output.
"NO"
AFTER REPAIRRepeat the conformity check from the start.
USM_V48_PR010 /USM_V4C_PR010
Page 75 of 94
ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Command summary table87G
87G - 75V7 MR-372-J84-87G050$715.mif
UPC
Vdiag No.: 48, 4CENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Command summary table
Tool command Diagnostic tool title
AC001Main beam headlights
AC002Dipped headlights
AC003Side lights
AC004Front fog lights
AC005Low-speed windscreen wiper
AC006High-speed windscreen wiper
AC008Compressor control
AC009Low-speed fan assembly
AC010High-speed fan assembly
AC011Rear screen de-icer
AC013Headlight washers relay
AC014Alternator regulation
AC016Test electrical supply circuits
MR-372-J84-87G050$715.mif
Page 87 of 94

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Interpretation of commands87G
87G - 87V7 MR-372-J84-87G050$770.mif
UPC
Vdiag No.: 48, 4C
AC014
ALTERNATOR REGULATION
NOTESConditions for the application of the command:
–engine running at idling speed and warm engine,
–air conditioning off,
–check that the passenger compartment blower unit is not operating.
–check that the cooling fan assemblies are not operating,
–if fault DF007 UPC-alternator connection is declared present, deal with this fault
first,
–check the conformity of PR010 Alternator charge (see Interpretation of
parameters).
Effect of command:
–for 30 seconds, the Protection and Switching Unit sets the alternator a regulation
voltage of 15 V ± 0.5,
–then for another 30 seconds, the Protection and Switching Unit imposes a
regulation voltage of 13 V ± 0.5 on the alternator.
Switch off all the electrical consumers (fans, main beam headlights, etc.).
Measure the voltage across the alternator terminals, between the B+ terminal and the alternator chassis earth.
Run AC014 Alternator regulation.
Wait 20 seconds,
For 10 seconds the alternator voltage should be 15 V ± 0.5.
Wait 20 seconds,
For 10 seconds the alternator voltage should be 13 V ± 0.5.
Switch on the heated rear screen and the main beam headlights.
Run AC014 again.
Wait 20 seconds,
For 10 seconds the alternator voltage should be 15 V ± 0.5.
Wait 20 seconds,
For 10 seconds the alternator voltage should be 13 V ± 0.5.
If the values obtained are not correct, replace the alternator (see MR 364 or MR 370 Mechanical, 16A, Starting-
Charging, Alternator: Removal - Refitting).
AFTER REPAIRRepeat the conformity check from the start.
Page 94 of 94

ENGINE COMPARTMENT CONNECTION UNIT
Fault finding - Tests87G
87G-94V7 MR-372-J84-87G050$935.mif
UPC
Vdiag No.: 48, 4C
TEST1
CONTINUED
With the engine running, main beam
headlights and heated rear screen on,
measure the voltage between the B+
battery feed and B+ alternator feed
Check the condition of all the wires connecting the
battery, alternator and starter and that all of their
terminals are correctly tightened. Is the voltage > 0.7 V?
Repair any damaged wires and terminals. If the
connection is faulty and if there is a repair
procedure (see Technical Note 6015A Electrical
wiring repair, Wiring: Precautions for repair),
repair the wiring, otherwise replace the wiring
With the engine running, main beam
headlights and heated rear screen on,
measure the voltage between the B- battery
feed and the alternator frame.Check the earths for the engine, the alternator, the
chassis, the gearbox, the battery or the starter
(check for tightness, check the condition of the
terminals and the condition of the wires) (see
Technical Note for the relevant vehicle). Is the voltage > 0.7 V?
Repair any damaged wires and terminals. If the
connection is faulty and if there is a repair
procedure (see Technical Note 6015A Electrical
wiring repair, Wiring: Precautions for repair),
repair the wiring, otherwise replace the wiring The electrical circuit is in good order.
A
YES
YES
NO
YES
NO
AFTER REPAIRCarry out a complete check with the diagnostic tool.
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