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 air mass meter

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 conditions

● Electrical consumers switched off (radiator fan must not run during the check)
● Air conditioner switched off

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 engine must be running at idling speed.
(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, 1 and 5 for "Display group number 15" and confirm entry with Q key.

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

Read measured value block 15 ⇒

1 2 3 4


	Display zones
	1	2	3	4
Display group 15: Load registration 1
Display	xxx rpm	xx.xx ms	xx %	xx.x g/s
Indicated	Engine speed	Engine load	Engine load	Air mass
Working range	800...6000 rpm	0.00...25.00 ms	0...40 %	---
Specification	800...880 rpm	1.00...3.00 ms	10...30 %	3.0...4.0 g/s
	---	If specification is not attained => Page 24-70 , check wiring		---

‒ Press C key.
‒ Press keys 0, 1 and 6 for "Display group number 16" and confirm entry with Q key.

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

Read measured value block 16 ⇒

1 2 3 4


	Display zones
	1	2	3	4
Display group 16: Load registrations 2
Display	xxx rpm	xx.xx ms	xx.xx ms	xx.xx ms
Indicated	Engine speed	Engine load	Engine load	Engine load substitute value from throttle valve angle
Working range	800...6000 rpm	0.00...25.00 ms	0...25.00 ms	0.00...25.00 ms
Specification	800...880 rpm	1.00...3.00 ms	1.00...3.00 ms	1.00...3.00 ms
	---	---	If specification is not attained , evaluating display group 16	---

Evaluating display group16


Display group: 16
Display zone: 3	Possible fault cause	Fault elimination
0.00 ms	Wiring open circuit in wire 3 or 4 between air mass meter and control unit	- Check voltage supply => Page 24-70
Smallest value: 5.30 ms	Wiring open circuit in wire 1 or 2 between air mass meter and control unit	- Check wiring => Page 24-70

Checking voltage supply

‒ → Pull 4 pin connector off air mass meter.
‒ Connect multimeter with aux. cables from V.A.G 1594 to measure voltage at contacts1+3.
Specification: 9.0...14.5 V

If no voltage is present:

Checking wiring



‒ Switch off ignition. ‒ → Connect test box V.A.G 1598/18 to control unit wiring loom -arrow-.

‒ → Check wiring between test box and 4 pin connector for open circuit according to current flow diagram.
     Contact 2+socket 16
     Contact 4+socket 17
     Wire resistance: Max. 1.5 ω
‒ Additionally check 4 pin connector wiring for short to one another.
Contact 4+socket 16
Specification: ∞ω
‒ Set multimeter to "Voltage measurement" range.
‒ Check 4 pin connector wiring for short to battery + according to current flow diagram.
     Contact 2+vehicle earth
     Contact 4+vehicle earth
     Specification: 0 V

If no wiring fault is detected:

Volkswagen Workshop Service and Repair Manuals