[gerent2]

Hey all. Car has been sitting for two years. I revived it but I'm chasing down errors. I can clear codes and everything seems to work fine for about 5 minutes. Then I get a bunch of warning lights for MSP, EPB, ASR, etc. After that I get suspension failure and power steering failure warnings and the speedometer goes to 0.

I suspect this is why I'm getting errors on all these systems. They all require vehicle speed to function. It is the ABS computer that drops first and then everything else follows. My issue is that if I monitor the NFR data stream I can see all four speed sensors report properly until I eventually get the error on the dash and then they all shoot up to 86mph and freeze there. I don't see a single wheel speed sensor not reporting or reporting vastly different than the others. The 86mph reading might also just be a signal error from whatever the actual problem is.

Recent work performed on the car:

Skyhook module (was reporting inability to to communicate with can bus)
Alternator (completely died)
Battery
Oil change

Voltage is good at 13.6. As far as I can tell, all my grounds are good and connections at the battery are solid. I'm pulling my hair out here. I don't want to replace the ABS computer and just throw parts at the car. I'm acutely aware (thanks to this forum) to ensure that I have good power and indeed I do.

The codes I'm getting after a fresh reset followed by a 5 minute drive are:

NCM Engine Node

• P0500 - Vehicle Speed Signal (Incorrect Working)

EPB Electronic Parking Brake Note

• U1213 - Invalid signal from ESP CAN Line
• C1622 - Incorrect Processor Request (Master-Slave Incoherence)

NFR Braking System Node

• C1250 - Temporary Interference
• U1713 - Parking Brake CAN Message Error

NCA Automatic Gearbox Node

• P0501 - VELOCITa Ruote Posteriori Non Plausible <--- Think it just means that the speed sensor data isn't plausible

NCS Skyhook Suspension

• U1706 - No Communication with NFR

When this error occurs I immediately lose my speedometer. I suspect this is why I'm getting errors on all these systems. They all require vehicle speed to function. My issue is that if I monitor the NFR data stream I can see all four speed sensors report properly until I eventually get the error and then they all shoot up to 86mph and freeze there.

Recent work performed on the car:

Skyhook module (was reporting inability to to communicate with can bus)
Alternator
Battery
Oil change

Voltage is good at 13.6. As far as I can tell, all my grounds are good and connections at the battery are solid. I'm pulling my hair out here. I don't want to replace the ABS computer and just throw parts at the car.

 

[gerent2]

Parking brake works fine or at least seems to. It engages and disengages fine. I think that problem is a symptom of something else because that EPB error comes on at the same time as the other errors. I can sit in the driveway and engage/ disengage the parking brake with no issues and I'll never get a light.

The suspension module for this car is under the driver's feet. It's already been replaced. Prior to this it was saying it had a canbus error and wouldn't show me sensor data. Now it seems to work fine but fails after I get the warning lights for the brake system.

What I'm speculating is happening is that I'm losing the NFR Brake Computer, that is preventing vehicle speed from being transmitted and then everything else that relies on that suddenly goes nuts. The suspension is telling me it can't communicate with the brake node. So that seems to suggest that the brake node is the common denominator. I was just hoping for some insight/ experience from others before I replace the brake computer.

 

[gerent2]

Bump. Semi-desperate here. My next move is to just throw parts at the car and I hate doing that.

Right now I’m between tires and an ABS computer. I wish this forum was more active. I feel like it this is a common enough problem that someone has some insight.

Today I noticed that the car tried engaging traction control and limiting power under moderate acceleration. That seemed odd and eventually it errored out, threw up all its warnings and gave up. That’s when it lost the speedo.

I decided to check the tires and noticed the dealer put two new 245 45 20’s up front. Those are substantially larger than the stock 245 35’s.

I also read the data stream and noticed the speed variance between front and rear wheels.

So now what I think is happening is that the brake computer can not reconcile the difference between front and rear wheel speeds, is erroring out and taking any module that requires vehicle speed with it. This also explains why I’m not getting a specific sensor failure code. The car wouldn’t know what set of wheels is giving accurate information and which isn’t. It would just know that the data is implausible.

So then here’s my question. Hopefully a really simple one. When this happens I get the Christmas tree of lights and lose my speedometer however i can still read the raw vehicle speed sensor data through my scanner. Is the loss of speedometer normal for when the ABS computer detects a vehicle speed issue on one or more wheels?

I think my skyhook module for not being able to communicate with the NFR might be a symptom of the NFR going into error mode and/ or a symptom of my scanner putting it into dish mode and taking it offline for a moment.

Thoughts?

Boy I sure hope this helps someone with this oddly specific problem down the road. 😂

 

[gerent2]

I can feel your frustrations but I don't think this forum is about getting tech support to repair your car.

Myself and a handful of others here give help out of the goodness of our hearts. We can give advice and only make some suggestions.

I think tech support, hands on experience with specific problems and shared experiences are exactly what forums are for. Ive owned and worked on a wide variety of cars and been involved with a bunch of communities over the years and that’s exactly how this has worked.

ok

What's on the rear?

Definitely something not good.

I would agree

I my opinion no but I'm not an engineer and unless one had encountered that fault before then one would probably not know the answer to that question.

Which is why I’m here trying to ping the collective experience of the community to see if anyone has had this exact situation.

I think at the point you noticed the different tire sizes you should have made that correction. Then after the correction if it still had a problem then ask for more help.

I noticed the tires last night and figured I’d ask here to see if I’m barking up the right tree. There was nothing I could do about it last night.

Hopefully what people can learn from this is to correct first what you see wrong and then continue on from there before wasting more time than needed.

My man, how condescending and presumptuous.

Last thing, your comment " I wish this forum was more active. I feel like it this is a common enough problem that someone has some insight" was enough for most to not even want to answer you because it was a bit rude. Only because I'm such a nice guy that I did and to say to anyone out there that may be trying to repair their car on their own to always fix first the obvious then continue on from there. Hope this helps someone.

Whatever you think you offered because you’re a nice guy, it wasn't assistance. Nobody would look back on this post and be like “boy that comment where maseratibychoice said “ok” and “I agree” is what really helped me solve my problem!”.

You came in here and did some head nodding, criticized my approach, offered no specific technical insight whatsoever and then told me what a nice guy you were for doing all of that in spite of my desire for this forum to be more active, which by the way, isn’t a dig at the forum or its members. So I’m not sure how you arrived at that conclusion.

Active forums have many voices with varying experiences and many data points. People share their first hand experiences, what works, what doesn’t work, etc. This isn’t a very active forum so you don’t really get that here. It’s nobody’s fault and I’m grateful for all the data that is here already.

 

[gerent2]

That seems entirely plausible



Again plausible but I cant imagine anyone other than the engineers that coded the system could say with certainty.

I think you've got a good shout with the tyres. It all seems logical

C

Yeah I can’t imagine it’s not the tires. It’s a 2” difference in height between 245 35 and 245 45.

Will try and report back with findings!

 

[gerent2]

So I found the problem. I’m going to preface this by saying, I’ve worked on some odd cars. Some exotic. Some obscure. Some exotic and obscure. But I have never worked on something with an electrical system as oddly implemented or as finicky as this car. It’s really something to behold.

Today I went for a drive and I wondered if perhaps turning off the traction control would affect my symptoms at all. I didn’t really think this would affect anything because if the variance in wheel speed exists with the traction control on, it also exists with it off.

But it turns out disabling it results in the system never erroring out because it’s not seeing false wheel slip and trying to reconcile that.

So what I think is happening is when traction control is on, the car thinks it’s experiencing wheel slip because of the variance in speed between the front and rear wheels. Eventually it realizes it can’t reconcile this difference and can not fix the wheel slip and thus assumes the data it is received is implausible and disables itself. This is when you get the ARS, MSP, and ABS lights. And then in my case: power steering and suspension failure as well.

Now the fun part is how the system works once it disables itself. It appears to just nuke its output. Your speedometer goes to zero and any subsystem that relies ok vehicle speed data spits up an error.

So a very basic problem needlessly takes down a bunch of other systems with it. It’s really wacky. In most cars what happens is traction control tries to engage, realizes that despite its efforts it’s not solving the wheel spin and so assumes its data is invalid and disables itself and only itself.

You never lose vehicle speed data and thus you never lose the use of vehicle systems that rely on this.

I’ve come to understand why these cars are notoriously finicky. Seemingly small problems result in symptoms that seem completely unrelated until you identify the common thread between everything that’s not working.

At any rate, it was the mismatched tires. So for that one guy that pops in here next year with the same problem, here you go buddy.