355 Custom 355mm BBK Upgrade - Now ABS light is ON

Just exactly what do you think should happen when the wear sensor <well> senses wear ???

 

Removing the pad wear sensor triggers the parking brake light actually. The sensor is just completing the circuit until the pad wears down and breaks the wire, it has nothing to down with grounding to the rotor. The brake light is triggered by the fluid level sensor among other things.

It's also possible that you disabled ABS via the center console button.

 

From the WSM

Abnormalities indicated by the ABS warning light in the form of numerical codes (two figure numbers from 11 to 78).

The operator may request decoding of faults stored in the electronic control unit whether these are still present at the time of the check or occurred by chance then disappeared (e.g. radio interference induced by external environment).

Proceed as follows:
1-with the car at a standstill (do not turn wheels if the car is raised),
check that ignition is off.
2- Insert a normal fuse (5 or 10 amps) in fuse holder E, Fig. 26 (in order to earth control unit pin no. 26).
3 -Turn ignition key to MARCIA position and observe the behaviour of the ABS warning light which should have come on in the meantime. li it goes off after 4s and stays off, the control unit has no electrical defects.

Deletion of (ABS) memory:

After displaying all anomalies and carrying out all necessary repairs, remove fuse E, Fig. 26 and road test the car. When a speed of 40 kph has been exceeded, if no further faults occur or are identified, the memory is deleted. In the case of further anomalies, the ABS warning light comes on to show that more checks and repairs need to be carried out Note: the memory can be deleted only if all error codes memorised have been displayed at least once, to the end of the sequence.

 

It won't melt

 

Don't know where you guys are getting your information from regarding brake wear indications. 12 volts power is supplied to the brake warning light from the AC System fuse. The light needs an earth (ground) to turn on.

Brake warning light diagram here:

https://www.dropbox.com/t/EXDVPJJA9PQHrHiR

Also, Bosch brake system diagram here, showing fluid level sensor:

https://www.dropbox.com/t/O0QbixSA7vIaUmkG

 

Image Unavailable, Please Login Re: Teves brake pad sensor

 

I missed that detail. Disregard the above, Bosch owners.

Diagnostics require an SD1 for the Bosch 5.3.

There's a drive cycle like procedure in the manual to "relearn adaptations" but it's too long to copy here

 

I was referring to how the sensor itself works, not the broader system. It doesn't take a genius to deduce the instrument light is controlled via earth.

@Qavion PS. Would you mind PMing me what electrical diagrams you have for the 355? Those are exceptionally clear and detailed.

 

See G31 through G37 in Volume 2

 

That's Volume 1. Do you not have Volume 2?

 

That doesn't explain why you said this @sfcarguy :

Removing the sensor removes the possibility of the sensor providing an earth to the light.

 

All of them? Do you have a 2.7 or 5.2? F1? Gated? Spider? What part of Earth are you from?

 

I’ll preface this by saying one of us clearly doesn’t understand what the other is suggesting, I’m not here to pick a pointless argument, and that if I’m wrong I’ll gladly accept the fact. You are an expert on the electricals of these cars after all.

Every single stage brake pad wear sensor I’ve ever had hands on has been a closed circuit that triggers the light by wearing down and becoming an open circuit, either through a relay or the ABS brain. Grounding to the rotor itself has no impact on the function of the wear sensor circuit. Not having any sensor connected would trigger a warning, and that’s why many bypass the circuit when installing race pads either by bridging wires together or tucking a new sensor out of the way.

What I think you’re suggesting is that the 355 pad wear sensor circuit is normally open. That would mean as the pad wear, the sensor contacts the rotor thereby completing the circuit and triggering the light. However, that doesn’t make sense to me because a) that would mean the light is only on solid when the brake pedal is depressed and the pad and sensor are actually touching the rotor with low enough resistance for a little instrument bulb to light up, and b) your diagram (fig5) shows the sensor as connected to a spade on the hub (aka ground) with the sensor in between the ground and the dash light. How would the pad sensor grounding to the rotor trigger the light versus being grounded to the hub?

Secondly, if you really wanted to figure out where I’m sitting right now, you could’ve made a decent guess from my username. There aren’t very many cities with that abbreviation. I put ‘Earth’ as the location in my bio because I think it’s funny. If that doesn’t satisfy you, I’m happy to have a private conversation with you that isn’t searchable on the web if you’d like to know more about me.

Thirdly, I have a Euro 2.7 GTS. However, I will take EVERY (yes, everything) diagram you’re willing to send me. I like to hoard useful info as much as possible because the links in these threads generally stop working after a few years and who knows where all of the model experts will be if I need a diagram a decade from now.

 

Exactly what I’m trying to say

 

@sfcarguy

I'm always happy to be corrected, but this is one reason why I don't like giving out my diagrams in batches to be sitting on someone's harddrive not being updated when new information comes along. My HVAC diagram is up to its 38th iteration. My brakes diagram was simply based on the original, and there is no mention of a resistor. A switch symbol is shown.

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I am by no means an expert on car electrics. I just know how to read basic wiring diagrams. I'm just having trouble visualising the circuit mentioned in @C-speed 's post. How does the wire loop break cause a reduction in resistance? All that is at the other end of the circuit is a standard light bulb and power. If someone can provide me with a circuit diagram, I'll modify my brake diagrams (including all the other types, Testarossa, 512TR, 456M, 550, 348, 360, 430, although the later cars may have different technology).

There are other reasons for me not wanting to hand out my diagrams en-masse and that is I don't learn anything new (as I'm doing today). And I get less satisfaction, not being able to help people.

Anyway, here are all my 2.7 diagrams:

https://www.dropbox.com/t/QIHA95DsYMIlEkDS

I've left the USA lighting diagram in there. Also, there are some Spider diagrams.

Caveats:
There are a few unknowns regarding the engine harnesses. Some owners have noticed that the wiring differs from the OEM versions. I've labelled these diagrams "1994" (OEM) and "1995" (updated).
There is an alarm diagram, but this is only provisional.
I originally thought that the instrument panel internal wiring was the same (and only the bezels and external wiring were different), but variations have been noted (recently). I can only give a 90% probability that the instrument diagram is correct for your car.
Since you have a Euro car, you may have an ABS cutout switch. That is included in the brakes diagram, but USA cars may have a jumper wire fitted to plug 10009.
I don't know if the GTS has any differences regarding the dome light.
I haven't added a graphic for the USA-style ignition switch plug (but it's shown in a recent thread).
I don't know if your car has undergone any modifications regarding external lighting (for regulation purposes)

Maybe I should add these caveats to my zip files in future.

By the way, I only asked you what part of the world you were from to know which diagrams to send you (USA/Canada or ROW). I didn't want to invade your privacy. Perhaps I should have asked you where your car was from instead. You can never assume. I assumed "SF" was San Francisco, but it could have been for Scuderia Ferrari or something else.