Ignition System

General Infoexpand_more

Starters Spark Plugs & Plug Wires Firing Order Distributor Components Coils Ignition Control Unit Pin-outs Load Reduction Circuit Starting Battery

Troubleshootingexpand_more

Intermittent Starting No Start No Restart When Hot

DIY Guidesexpand_more

Setting the Timing Testing Ignition Switch Replacing Ignition Switch Ignition Tune-up Installing Hot-start Relay Bypassing Starter Interlock (A/T) Starter Service Bulletin (A/T) Removing Starter (A/T) Replacing & Servicing Starter Intalling New Starter Bushing Testing Hall Sender

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Starters

Everything you should know about VW starters and solenoids*:

The above link includes:

• How it's made
• Upgrading
• Replaceable parts
• Troubleshooting
• Lots of starter issues are wiring related
• Sometimes it starts, others not
• Starter stays on even when driving or after the car is shut off
• It grinds like a mofo!
• OK, the starter is out, how do I know if it's good?
• Slowwwww cranking
• The starter spins, but doesn't engage the flywheel
• Replacing the starter

* Diesel starter is shown/used in that link. Diesel starters contain reduction gear sets and are larger and heavier than gasoline starters.

Intermittent Starting

Causes and remedies:

• Ignition switch is faulty. Replace ignition switch.
• Starter is faulty. Replace starter.
• Faulty battery cables and/or electrical connections. Replace battery cables and/or clean/repair electrical connections. Be sure the ground connections are good. Note: Replacing the battery cables is a wise idea whether or not your car is suffering from starting issues.
• 1990+: Coolant temp sensor (CTS) is faulty. Replace blue CTS.
• Cabriolets with automatic transmissions:
• Not starting when hot: Starter is suffering from heat-soak. Install a hot-start relay and be sure the heat shield is in place.
• Intermittent starting: Starter-interlock system is faulty (1990+). Replace or bypass the interlock relay.
• Fuel pumps are overheating. Replace fuel pumps.
• Fuel pump relay is faulty. Replace relay.

No Start

For complete diagnostic procedures for all of the above, please refer to your Bentley Service Manual (or other repair manual).

No Restart When Hot

Is it an automatic? Automatic Cabriolets are notorious for this problem due to the poorly-located starter (next to the exhaust manifold). The best solution for this problem is to install a hot-start relay. Also, be sure that the heat-shield is in place.

Installing a hot-start relay:

Spark Plugs & Plug Wires

Spark Plugs

Spark plug guide:

Spark Plug Wires

Bosch is still making decent wires, so they are still recommended. However, NGK is now making a set of plug wires for these cars, which are also recommended (#VWC013, or NGK57283). NGK wires include cylinder number labels; these do not correspond to 1979-1993 Volkswagen inline-four engines. Ignore these labels and install them one-by-one, according to your old plug wire lengths.

Firing order: 1-3-4-2

Distributor Components

Ignition distributor component guide:

Ignition Coils

Ignition coils guide:

Ignition Control Unit Pin-outs

Load Reduction Circuit

Also known as the "X" circuit, the load reduction circuit is exactly that: It is the circuit that reduces the load on the ignition system during cranking by cutting power to high-load accessories. These accessories include the headlights, the HVAC system, windshield wipers, and rear window defroster.

More thorough explanation and troubleshooting can be found at this link.

Battery

North American Cabriolets were originally equipped with Group 41 lead acid batteries. These are now becoming harder to find in some regions, but there are other options available; refer to the guide below.

Starting battery guide: