Cabby Info - Tech Service Bulletins

Updated: 28-Mar-2025

This page contains a list of Volkswagen's Technical Service Bulletins related to 1980-1993 Cabriolets. Technical Service Bulletins (TSBs) are documents issued by car manufacturers to inform dealer service technicians about specific, non-safety-related issues and provide guidance on how to diagnose and repair them. Unlike recalls, TSBs are not mandatory repairs, and the manufacturer does not require dealerships to perform the repairs and reimburse them for it, unless the vehicle is under warranty. Not all TSBs are listed, just the most prominent, and for historical purposes only.

Air Conditioning

TSB number: 92-02 (supersedes 87-92-01)
Date issued: December 31, 1992
Subject: A/C Compressor Belt
Production: From 1990 model year
Problem: Because of the restricted space in the engine compartment, adjusting the A/C compressor belt via the toothed rack tensioner is only possible using the procedure described in this bulletin.
Service: A/C compressor belt, adjusting:

Body

TSB number: 87-03
Date issued: July 15, 1987
Subject: Vent Windows
Problem: Vent window sticks to weatherstrip seal
Service: Vent windows that adhere to the weatherstrip should be separated from the weatherstrip using a knife blade.

Apply silicone or talcum powder to the contact surfaces to minimize sticking.

Brakes

TSB number: 91-01
Date issued: June 30, 1991
Subject: Drum Brakes - Rear Wheel Brake Cylinder
Problem: Replacement criteria
Service: Rear wheel brake cylinders need to be replaced when one or more of the following conditions are observed:

Cooling System

TSB number: 90-01
Date issued: November 30, 1990
Subject: Radiator Fan, all models with A/C
Problem: Radiator fan stays on high speed
Condition: At high ambient temperatures of 105°F (41°C) and above, the radiator cooling fan stays on high speed with the ignition off, discharging the battery. At these ambient temperatures, gas pressure of the R12 refrigerant activates the A/C high pressure switch and triggers the high speed radiator fan relay.
Service: Replace the radiator fan high speed relay with Part No. 321-919-505A and modify the A/C high pressure switch wiring as follows (refer to applicable wiring diagram):

TSB number: 93-01
Date issued: June 1, 1993
Subject: Coolant Pump
Problem: Coolant pump leakage, warning lamp on
Service: Identify leakage.
NOTE: Do not confuse a leaking coolant pump with one that is functioning as designed. Coolant pump seals are designed to use coolant as a lubricant. This design intentionally uses a small amount of coolant to coat the seals during pump operation. Any excess coolant that accumulates will exit the weep hole when the engine cools down. Minute traces of coolant or lubricant residue around the weep hole is NOT evidence of a faulty pump.

Guidelines for coolant pump replacement:

Pumps have been incorrectly replaced because of: NOTE: DO NOT replace coolant pump without a valid reason. Before replacing, verify by testing that a legitimate pump leak exists.

Troubleshooting: Coolant level warning light, checking:

Electrical

TSB number: 92-01
Date issued: January 31, 1992
Subject: Alternator V-belt
Problem: Alternator V-belt may slip under extreme load conditions.
Service: To prevent possible alternator V-belt slippage, the belt tensioning specification and adjustment procedures have been modified. When a customer complaint of V-belt slippage is encountered, adjust V-belt tension according to the specifications listed below.
Tensioning Specifications (The following values apply when using the "thumb pressure check" procedure.):

Adjustment procedure:

TSB number: 87-03
Date issued: July 15, 1987
Subject: Charging System
Problem: Battery indicator light flickers, battery discharged.
Service: Charging system troubles can be caused by loose eyelet connectors at the alternator. Replace the nut and eyelet connectors if a brownish discoloration is visible. This condition is a result of high resistance.

Torque: The small nut (8 mm wrench) on terminal D+ to 3 Nm (2.2 ft. lb.) The large nut (13 mm wrench) on terminal B+ to 16 Nm (12 ft. lb.)

Emissions

TSB number: 93-02 (supersedes TSB 92-01)
Date issued: July 31, 1993
Subject: All, 1980-1993
Problem: Oxygen sensor failure due to silicone contamination
CAUTION: Do NOT use any sprays or compounds containing silicone on engines equipped with Oxygen Sensors. Do NOT use these compounds on or near the intake air system or near the Oxygen sensor. Silicone drawn into the intake air system is not burned during combustion and will lead to contamination and malfunctioning of the Oxygen Sensor.

Engine

TSB number: 87-02
Date issued: July 15, 1987
Subject: 1.8L Engines with K-Jetronic
Problem: Lack of acceleration
Condition: Lack of acceleration may be due to limited sensor plate travel caused by an inverted or deformed screen in the sensor plate boot.
Service: Fix crushed airflow sensor boot screen.

TSB number: 88-04
Date issued: September 7, 1988
Subject: 1985-1987
Problem: Hot Start Difficulties
Service: On vehicles experiencing hot starting difficulties, install radiator cooling fan after-run kit Part No. 191-998-215:

TSB number: 89-01 (supersedes TSB 87-03)
Date issued: January 31, 1989
Subject: All 1.8L engines
Problem: Metallic Clicking Noise
Condition: A light metallic clicking noise may be heard when engine is at operating temperature between 800-1200 RPM or 1800-3000 RPM. This is caused by tolerances at the connecting rod/piston pin, which is not detrimental to the expected service life of the engine. For customers who insist that the noise is unacceptable, a service repair kit, P/N: 026 198 399C, has been introduced to remedy the noise complaint.
The service repair kit consists of the following parts:


Service: When installing the service repair kit, note the following:

TSB number: 93-07
Date issued: November 15, 1993
Subject: Digifant engines, 1990-1993
Problem: Lack of Power, Stalls, Bucking, Jerking
Condition: After one half to two hours driving at a constant speed, the vehicle lacks power, cuts-out or stalls, often accompanied by bucking or jerking. In all cases the vehicle will restart immediately. The condition may not recur for several weeks or months. Subsequent service inspections produce inconclusive results. Some airflow sensors can have a vibration resonance of the metering potentiometer wiper during an extended drive at constant speeds. The resonance causes the airflow sensor to supply an intermittent signal to the ECM. The ECM will then default to a "no load" condition and reduce the injection time.
Service:

TSB number: 93-10
Date issued: December 15, 1993
Subject: Digifant engines, 1990-1993
Problem: Rich engine running condition
Condition: A rich engine running condition may be caused by an improper or loose Engine Control Module (ECM) and Oxygen Sensor (02S) Ground (GND) connection.
Service:

TSB number: 94-01
Date issued: January 20, 1994
Subject: All engines, 1980-1993
Problem: Poor driveability
Condition: Poor driveability may be caused by magnetic interference due to a deteriorated Oxygen Sensor (O2S) wire shield or improper Oxygen Sensor (O2S) wire shield Ground (GND) connection.
Service:

TSB number: 93-04
Date issued: November 15, 1993
Subject: Digifant I, Digifant II
Problem: Poor idle/Stalls, Loss of Power, Exhaust Smoke, MIL/CEL on
Condition: A driveability problem can lead to the replacement of the Engine Coolant Temperature (ECT) Sensor when it in unnecessary to do so. The following observations can lead to a suspected faulty ECT Sensor:

Suspected ECT Sensor problems can be caused by:
Service: Follow these steps to avoid unnecessary repairs when diagnosing suspected ECT Sensor problems:

Fuel System

TSB number: 93-02
Date issued: June 15, 1993
Subject: Digifant engines, 1990-1993
Problem: Faulty knock sensor
Condition: Here are some tips to follow if you suspect that a driveability problem is being caused by the knock sensor system.
Knock sensor malfunction may cause the following symptoms:

Knock sensor malfunctions may be caused by:
For example, a rhythmic knocking noise from a malfunctioning A/C compressor that increases and decreases with engine RPM could be interpreted by the knock sensor as engine knock.
Service: To avoid making unnecessary repairs, use the following steps when diagnosing suspected knock sensor problems.

TSB number: 93-06
Date issued: November 15, 1993
Subject: Digifant I and II, 1990-1993
Problem: Hunting Idle
Condition: After initial cold starts, the idle speed hunts for approximately one minute. After this period, the idle speed returns to normal.

Idle hunting is an indication of a properly functioning idle air control system trying to compensate for varying fuel/air mixtures.

Proper fuel/air mixture is required at all phases of operation. Idle hunting is in many cases caused by improper fuel mixture during the initial start-up phase. The Idle Air Control (IAC) Valve attempts to compensate for a low RPM by opening wider, increasing the air flow and in turn increasing the fuel injection time. When the mixture burns completely, the RPM will increase and the IAC will close. Idle hunting is due to the rapid opening and closing of the valve.

Replacing the Idle Air Control (IAC) Valve will not resolve this condition. To ensure proper diagnosis and replacement of the IAC valve, you must get prior repair authorization from your Warranty Adjuster or your DSM.
Service:

Ignition, Starter

TSB number: 92-02 (supersedes TSB 91-01)
Date issued: February 29, 1992
Subject: 010 Automatic Transmission
Problem: Does Not Engage/Restart When Engine is Hot
Condition: Starter motor does not engage during restart when engine is hot. The starter motor is heated up by the engine. During cranking, the voltage at terminal 50 of the starter solenoid must be at least 10 Volts. This value will not be reached at times by older vehicles.
Service:

TSB number: 93-10
Date issued: December 15, 1993
Subject: Digifant engines, 1990-1993
Problem: Rich engine running condition
Condition: A rich engine running condition may be caused by an improper or loose Engine Control Module (ECM) and Oxygen Sensor (02S) Ground (GND) connection.
Service:

Interior

TSB number: 91-02
Date issued: November 30, 1991
Subject: Seat Cover Beading
Problem: The lower seat cover beading is supported by a flexible plastic piping. This piping slowly slips out of the beading and becomes visible.
Service: Cut visible plastic pipe off. Then glue the beading openings closed.

TSB number: 92-01
Date issued: April 30, 1992
Subject: Defroster Vents, 1990-1991
Production: Production assembly modified as of 02/91, VIN 15MK020420
Problem: Vinyl coming loose from the dashboard around the edges of the defroster vent openings may affect the direction of air flow.
Service: In case of customer complaint of inadequate defroster function, install plastic inserts into the defroster openings. Part No. 171-857-461C Qty. 2 and Part No. 171-857-461B Qty. 4

Suspension & Steering

TSB number: 90-03 (supersedes 89-02)
Date issued: September 30, 1990
Subject: CV Joints - all models
Problem: Revised diagnosis, inspection and replacement
Service: Locating a noisy CV joint:

Inspection and replacement:

TSB number: 89-03
Date issued: August 31, 1989
Subject: Power Steering Fluid
Info: Beginning April 1989, the power steering will be filled with hydraulic oil, instead of ATF. It is the same hydraulic fluid used in Audi vehicles.

Part Number: G002000

This hydraulic oil exhibits good viscosity behavior especially during cold temperatures. In countries with cold temperatures, it is recommended after repair work is performed on the power steering that only G002000 be used to refill. This formula can be used on ALL current production vehicles.

NOTE: Hydraulic oil G002000 can be mixed with ATF.
CAUTION: Part numbers are for reference only. Always chock with your Parts Department for latest information.

Transmission - Automatic

TSB number: 91-02
Date issued: May 31, 1991
Subject: 010 automatic transmission
Problem: Shifts Erratically
Condition: Automatic transmission shifts erratic due to leakage between automatic section and the differential section of the transaxle.
Service:

TSB number: 91-02
Date issued: April 30, 1991
Subject: 010 automatic transmission
Problem: Ticking Noises at 1800 to 3200 RPM
Condition: Engine noise may be amplified by the torque converter drive plate.
Service: Install modified drive plate, Part No. 053-105-323E.

Transmission - Manual

TSB number: 93-04
Date issued: June 15, 1993
Subject: 020, 02A, O2B manual transmissions
Problem: Difficulty Shifting In and Out of Gear
Condition: Transmission intermittently difficult to shift in and out of gear.
Service: Ensure that the shift linkage and clutch free play is adjusted properly and is not causing the complaint. If the shift linkage is adjusted properly proceed as follows:

TSB number: 40-90 T01
Date issued: May 31, 1990
Subject: 020 transmissions
Problem: Flanges on Remanufactured Transmissions
Service: Remanufactured transmissions are assembled with either 90 mm or 100 mm flanges. When you replace a transmission with a rebuilt unit; do not replace drive shafts to match to the flanges. Instead replace the flanges to match to the drive shafts.
In case of replacement, remove the new flanges from the rebuilt unit and exchange them for new flanges that match the existing drive shafts. Your Parts Department will provide you with the exchange flanges. Also, please remember to use new flange seals.

TSB number: 87-01
Date issued: July 31, 1987
Subject: 020 transmissions
Problem: Grinds into 1st/Reverse/Hard shifting - clutch disc binding
Service: Grinding when shifting into 1st or reverse may be due to incomplete clutch disengagement caused by the clutch disc binding on the mainshaft.

When installing a clutch disc, thoroughly clean splines of disc and mainshaft with a wire brush and lubricate with MOS2 grease, Part Number G000602. Ensure disc slides freely on shaft before assembly.



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