FAQ
TL;DR: 2 body-side connectors sit under rubber caps; "Make jumpers, but not at the wheels, but in the body." This FAQ helps Audi A4 B5 owners stop recurring pad‑wear lights after sensorless pads or weak splices, using connector jumpers for diagnosis. [Elektroda, Jackall, post #17051866]
Why it matters: It shows how to quickly isolate wiring vs. sensor issues so you can fix the warning without guesswork.
Quick Facts
- There are 2 body-side connectors under rubber caps: one ABS and one pad‑wear circuit. [Elektroda, Jackall, post #17051866]
- Rear pad‑wear sensors on A4 B5 1.6 '99: 0 (unless RS brake swap). [Elektroda, osiniak75, post #17051724]
- Low brake fluid can light the indicator; confirm reservoir is between MIN and MAX. [Elektroda, osiniak75, post #17051575]
- Diagnostic tip: fit a jumper and drive 2 days to confirm a faulty sensor/harness. [Elektroda, citromaniak, post #17073031]
- Software route exists: pad‑wear warning can be turned off via VAG tools. [Elektroda, bodzio012, post #17052135]
How do I fix a pad-wear light that returns after bridging at the caliper?
Bridge the circuit at the body-side connector, not at the wheel. Corrosion or breaks between the body plug and caliper often cause intermittent opens. Find the two rubber-capped plugs and jumper the pad-wear one to test. If the light stays off, repair that harness segment. If it persists, the issue is upstream. "Make jumpers, but not at the wheels, but in the body." [Elektroda, Jackall, post #17051866]
Does a 1999 Audi A4 B5 have rear pad-wear sensors?
No. The standard A4 B5 does not have rear pad-wear sensors. An exception is if someone fitted RS-spec brakes. "There are no sensors on the back unless you have brakes from the Audi RS." That means rear pad wear will not trigger the warning on the stock setup. [Elektroda, osiniak75, post #17051724]
Can low brake fluid trigger the brake pad warning?
Yes. Low fluid can illuminate the same warning in this platform. Confirm the reservoir is between MIN and MAX, and inspect for leaks. Quote: "As with the level of brake fluid, at low levels it can also ignite." If topping up helps only briefly, diagnose the level sensor and system for losses. [Elektroda, osiniak75, post #17051575]
How do I jumper the pad-wear circuit at the body connector?
Use this 3-step check:
- Locate the two rubber-capped connectors in the body near the wheel; identify the pad-wear plug.
- Insert a shorting jumper across the pad-wear connector to close the loop.
- Start the car and drive; if the light stays off, the fault is from that plug to the caliper.
This isolates harness or caliper-side faults cleanly. [Elektroda, Jackall, post #17051866]
How can I quickly test the brake fluid level sensor?
Unplug the brake fluid level sensor and fit a small jumper across its pins to simulate a healthy level. If the warning clears, the level sensor or its float is faulty. If it stays on, continue wiring diagnosis and pad-wear loop testing. Restore the original connection after testing. This quick jumper test narrows the cause fast. [Elektroda, citromaniak, post #17051681]
Unplugging the pad sensor made the light stay on—normal?
Yes. The pad-wear circuit is monitored for an open loop. Unplugging creates an open circuit and keeps the warning illuminated. To extinguish the light without a sensor, you must close the loop with a reliable jumper at the correct connector. Soldering helps only if all segments of the loop are sound. [Elektroda, Pitol2710, post #17051577]
Refilling brake fluid cleared the light briefly; why did it return?
The level likely hovered near the trigger point or the level sensor is intermittent. After driving, the light returned as the level dropped or the sensor acted up. This pattern indicates you should verify the level again, inspect for leaks, and test the level sensor with a jumper. [Elektroda, Pitol2710, post #17060530]
Can I just code the pad-wear warning off with VCDS/VAG-COM?
It’s possible to turn it off with VAG tools, but weigh safety implications first. The warning exists to protect braking performance. Disabling should be a last resort after proper diagnosis or when using reliable bypasses. Tools like VCDS make coding changes easy, but use them responsibly. [Elektroda, bodzio012, post #17052135]
Where exactly are the connectors I should jumper?
In the body near the wheel well, under rubber caps, you’ll find two connectors. One is ABS, the other is the pad-wear circuit. Bridge the pad-wear connector there to test the loop. This avoids wheel-end corrosion masking the real fault. There are two connectors total in that location. [Elektroda, Jackall, post #17051866]
How long should I drive after installing a jumper to confirm the diagnosis?
Drive about 2 days with the jumper fitted. If the light stays off, replace the failed sensor or repair the harness. If the light returns, look upstream at the fluid sensor or cluster inputs. This duration helps catch intermittent breaks and vibration-related faults. [Elektroda, citromaniak, post #17073031]
Will rear pad wear trigger the warning on my A4 B5?
No, not on a stock A4 B5. The system monitors front pad-wear only unless an RS brake swap was installed. So, focus diagnosis on the front circuits, connectors, and fluid level. Rear pad condition won’t set this indicator on standard cars. [Elektroda, osiniak75, post #17051724]
I installed pads without sensors; will buying pads with detectors stop the warning?
Yes, using pads with the correct wear leads restores the factory closed loop. If you keep sensorless pads, you must maintain a durable jumper in the circuit. Weak splices can flicker the light as the loop opens under vibration. [Elektroda, Pitol2710, post #17051552]
Why do some owners say unplugging clears the light, but mine stays on?
Cluster behavior and wiring states can differ across cars and years. One owner reported the light did not shine after unplugging, but your circuit likely detects open loop. Close the loop with a jumper instead of leaving it open. [Elektroda, nuszek, post #17051572]
What edge case keeps the light on even after I solder a jumper at the caliper?
Hidden harness damage near the body connectors can reopen the loop. Jumpering only at the caliper won’t bypass corrosion or breaks upstream. Move the test to the body-side pad-wear connector under the rubber caps to isolate that segment. [Elektroda, Jackall, post #17051866]
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