Hey all. Now that I solved my Battery light issue, it’s time to move on to the next and final issue I’m chasing. I have a 1995 F355 with the Teves ABS system. I’ve read a TON of forums on here about checking codes and such. My car has both the ABS and Brake lights showing on my dash. Once in a while they both turn off at the same time, but 75% of the time, they are both on. The shop I’ve taken it to says it’s the ABS ecu or module. I’ve also read online that those could also be found in similar, more affordable options. Any recommendations on where to start or how to confirm it’s truly the ABS module? I’m no mechanic, but want to see if I can at least figure out the culprit. cheers
On the 355, the BRAKE warning light is electrically unrelated to the ABS light. The BRAKE light can only be put on for low fluid or brake pad wear. Of course, if your fluid is low, this may affect the ABS system. Check fluid level. If low, look for leaks (including around the ABS module). The light may simply be due to a faulty level sensor on the reservoir. If the brake light appears, pull the electrical plug from the level sensor to see if the BRAKE light goes out. If no luck, check for front brake pad wear and wiring to the wear sensors. Is the wire insulation damaged and the wiring shorting to ground? On cars like the 360/430, they wired up the BRAKE and ABS warning lights so that any ABS issue would automatically also turn on the BRAKE warning light (but not vice versa).
Thank you! I’ll check this out. Just seemed strange that they are always tied together. Both lights are either on, or both off. Not just the BRAKE light or ABS.
Indeed. There is no wiring between the ABS Module and the BRAKE warning light in the dash. The only way to simultaneously illuminate them would be if there was a diode inside the dash between the two lights. I can't say I noticed one when I had my dash apart. Anyway, if there was a diode, the BRAKE light would always illuminate every time the ABS light came on.
Ooops... I just rechecked the wiring diagrams and realised that the BRAKE light also comes on with low brake pressure on the Teves cars. That would make more sense. On the Bosch system on my car, the BRAKE light doesn't look at pressure.
In light of this, perhaps the pump or the reservoir is faulty. Did your tech check these? Here's the pressure and level sensor wiring: Image Unavailable, Please Login On the pressure sensing module, different switches are used for: BRAKE light Pump Control ABS fault light. The ABS fault wiring loops through a pressure switch and two fluid level sensors. A ground/earth signal going to the ABS module = OK. A ground/earth signal going to the BRAKE light is not OK.
Ok, took it to the stealership today to diagnose, since I wasn’t figuring it out. They are saying it’s the ABS controller that needs replacing, and are quoting me $4,400 for a refurbished piece installed. I feel like I’ve read replacement parts on here from Fords and such. Is that an option for this piece, or am I stuck?
I don't understand why an ABS controller issue would cause the BRAKE light to illuminate. To get the BRAKE light on, you would need low brake pressure, low brake fluid or brake pad wear. Assuming your reservoir is topped up and your pads are good, the only thing left is low pressure. If you look at the wiring diagrams, the pump motor control relay coil is controlled by a pressure switch (not the ECU). There is another wire going to the relay coil from the ABS ECU (pin 14), but according to the Workshop Manual, this pin is not used. The pressure switch maintains the pressure within a certain band by opening and closing (within a certain range). https://www.dropbox.com/t/nT1Z6K8MA5zFpGec I think you need a second opinion on this or ask the dealer how he came to his conclusion. The system has a built in test which you can activate yourself, but it involves removing the front luggage liner to access the fuses. Maybe ask the dealer if he's willing to throw in the ECU for free (including installation costs) if he is wrong In this case, I don't think you can short out the pump relay to make the pump run continuously. The WSM has warnings about overpressure and causing permanent damage to the system. Because the symptoms are pointing to low pressure, I think I would be looking at the pump/reservoir assembly first. Has the dealer even tried a pump control relay? Maybe the pump control switches are faulty (although the pressure assembly doesn't seem to be available separately). Experts? @m.stojanovic Image Unavailable, Please Login
The pump can also be disabled (producing low pressure) by the engine start system. The key (in the start position) controls the orange "auxiliary ABS relay". If the relay contacts are faulty/intermittent, the pump may run intermittently. Note that this relay can be jumpered for faultfinding purposes without overpressuring the system. I would certainly be shotgunning the system with cheap components before committing myself to a U$4000 ECU.
This is based on the 348 diagrams but it should also apply to the 355 Teves. The ABS warning light can be switched on by the Main ABS Relay and/or by the ABS Computer (pin 27). These two ABS light triggering signals are separated by a diode in the "diode box" so that they do not affect each other when one of them triggers the ABS light. The signal from the ABS Pump pressure switch goes to the ABS Computer and the computer will trigger the ABS light if the minimum pressure is not achieved. If the Main ABS Relay does not engage at ignition "on", the ABS light will stay on. If the ABS Pump (accumulator) pressure is below the lower value, the ABS Computer will trigger the ABS light. Jaguar and Volkswagen ABS Computers appear to be very similar to the 348's. Ford ABS Computer internals look different but the functions and pinout might be same as the 348's. Below is the info I have on the possible alternative ABS Computers for the 348 (I have not tested any of these computers on my 348). 348 ABS pinout: Image Unavailable, Please Login JAGUAR Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login VOLKSWAGEN GOLF MK2, JETTA Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login FORD (no diagram) Image Unavailable, Please Login Image Unavailable, Please Login BUICK REATTA, CADILAC SEVILLE (I think there was a mention on the forum that this might be a possible alternative but I have no pic of internals nor diagram for it) Image Unavailable, Please Login
Agreed, but can you see any way that the ABS ECU internals would trigger the BRAKE* light? * (i.e. the exclamation mark in a circle on Euro cars) When looking for posts on the orange relay, I did find the thread which mentions starter relays causing issues: https://www.ferrarichat.com/forum/posts/149169232/
To your actual question about where to start: It’s usually best to start with the basics. 1. Do the brakes work ok or is the pedal hard all the time with no assistance? 2. Does the ABS work? 3. Does switching the ABS on & off (centre console) make a difference to the warning lights? 4. If you pump the brake pedal and empty the accumulator, does the accumulator pump run when you turn on the ignition? 5. After a while, does the pump stop, or does it run continuously? 6. Do the warning lights come on after you start driving or already before moving? Depending on the answers to the questions above you could have a faulty pump, wiring or power supply, a leaking pressure accumulator, faulty pressure sensors, faulty wheel speed sensors or wiring damage to the wheel speed sensors, very low brake fluid level, stuck valves/bad solenoids in the abs unit, or even (as has been suggested by your garage) a problem with the control modules. The key to this is to systematically try to find the root cause. Parts are so rare and expensive that we can’t just throw parts at them hoping to solve the problem. If the pump and accumulator are fine, then breathe a sigh of relief. There are quite a few threads covering the accumulator on here. Some people have had issues with the diagnostic fuse being left in, others with starter relay issues. It’s worth researching the many threads here. If you eliminate all the other potential issues, like wiring, fuses, wheel sensors etc. then you can narrow it down somewhat before hunting down a new control module.
I have a HUGE pile of ABS ECUs from Alfa Romeo Milanos (same as the 75 in Europe) that used the same MKII ABS system. I can also post the pinout to see if they are a good fit. If anyone wants one to test compatibility, just let me know and I'll send it out. Would be good to know.
Thank you ALL for responding! The dealer still has the car, but I’ll push back on their recommendation, or at the very least ask how they came to the conclusion of being the ECU. The car had an aftermarket alarm installed by the previous owner, which I had removed, but maybe that’s also something to verify isn’t the cause.
ALSO, for what it’s worth, the shop that did my engine out also believed it was the ABS ECU. So strange both places recommended the same, but also don’t know what exact testing they each did to verify. Brake pressure seems to be fine and I haven’t felt any concern in pedal feel. But once I get my car back, I’ll run through the different tests mentioned above.
Dealer said ABS module (part #148838) failed every part of the testing with their diagnostic tools. They are confident that is the issue.
Does this include ECU power supplied by the Auxiliary ABS relay to pin 2 of the ECU (with key on)? Unfortunately, we can't ask the dealer the questions we want to ask. When was the alarm removed (shortly before the ABS issues?)
ABS has always been on since I bought the car. BUT, only somewhat recently the brake light now also stays on. I wasn’t overly concerned about the ABS, but since both shops (dealer and independent shop) have said it’s the ECU, then I guess I’ll start with that. The alarm was removed a couple months ago but didn’t make a difference. I wasn’t the one to remove the alarm, as I had the shop to that, so Im curious if that is also playing into the starter like you’ve mentioned.
The Alfa ABS Computer internals look very similar to the Ford's, practically identical, i.e. they are somewhat different than the 348's. However, the functionality may be the same - needs to be tested. What I noticed on the Alfa ABS diagram is that the Computer pins 14, 26 & 32 are not used but they are used on the 348. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
That makes sense. One difference is that Alfa never implemented any fault memory on this system. There are no lights you can trigger to flash out code sequences, etc. The factory "tester", which I have, is plugged in between the ECU and wiring harness. You then use toggle switches on the breakout box (looks like a briefcase) to simulate various inputs and record the results. It is designed to test the other aspects of the system but by default can also test out the ECU itself.
Update… ended up picking my car up from the dealer since they couldn’t solve the issue. Replaced the ABS ECU per their recommendation which did not solve anything. I’m attaching the notes from the tech, which I’ll admit is over my head but does seem like he was very thorough.
