Volkswagen Workshop Service and Repair Manuals > Passat (B3) > Power unit | Motronic fuel injection and ignition system 08.95 | Mixture preparation system, electronic inj.,Gas | Motronic injection and ignition system

Motronic fuel injection and ignition system 08.95 ä

Motronic injection and ignition system

Checking control unit voltage supply

Special tools, testers and auxiliary items

◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
◆ Test box V.A.G 1598/18
◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
◆ Adapter set V.A.G 1594
◆ Current flow diagram

Test sequence

‒ Connect fault reader V.A.G 1551 (V.A.G 1552) and select engine electronics control unit with the "Address word" 01. When doing this the ignition must be switched on.
(Connecting fault reader and selecting engine electronics control unit .)

→ Indicated on display:

Rapid data transfer HELP

Select function XX

‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

→ Indicated on display:

Read measured value block HELP

Input display group number XXX

‒ Press keys 0, 0 and 2 for "Display group number 2" and confirm entry with Q key.

→ Indicated on display:
(1...4 = Display zones)

Read measured value block 2 ⇒

1 2 3 4


	Display zones
	1	2	3	4
Display group 2: General engine data
Display	xxxx rpm	xx.xx ms	xx.xxx	x.x
Indicated	Engine speed	Injection period	Battery voltage	Tank breather adaption value
Working range	800...6000 rpm	0.00...25.00 ms	0.000...16.500 V	---
Specific.	0 rpm	---	12.000...14.500 V	---
	---	---	If specification is not attained , evaluating display group 2	---

‒ Press ⇒key.
‒ Press keys 0 and 6 for the "End data transfer" function and confirm input with the Q key.

Evaluating display group 2

Display group: 2
Display zone: 3	Possible fault cause	Fault elimination
If no display appears on V.A.G 1551	Fuse 15 defective	- Replace fuse
	Wiring open circuit	- Check voltage supply terminal 15 => Page 24-112
If the figure displayed fluctuates between 12.0...14.5 V	Loose contact	- Check voltage supply terminal 30 => Page 24-111
0.0...12.0 V	Battery discharged/defective Voltage regulator defective	- Check battery Check alternator Check voltage regulator
14.5...16.5 V	Alternator defective Voltage regulator defective	- Check alternator Check voltage regulator

Checking voltage supply terminal 30

‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.
‒ Connect multimeter using aux. cables from V.A.G 1594 to measure voltage at sockets 1+54:
Specification: 12...14.5 V

If the specification is not obtained:

Checking voltage supply terminal 15

‒ Switch off ignition.
‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.
‒ Switch ignition on.
‒ Connect multimeter using aux. cables from V.A.G 1594 to measure voltage at sockets 1+23:
Specification: 12...14.5 V

If the specification is not obtained:

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