Electrical Problems - Anti-skid, brake failure, etc

[hughjass]

According to my mother the radio has not been working correctly and kept disconnecting from her phone.

I noticed the next day the radio was flickering on/off, and then the brake failure warning appeared on the dash, but I could still drive it and they stopped appearing after a while.

The next day it gave the brake failure and anti-skid errors. When I tried driving it, a few times it would just cut out. After a few attempts of driving for a minute and it cutting out, it refused to start. After leaving it for 30m it started and drove it in a low gear around the block and back to the house.
I checked the battery and it was 12.6v. After starting the car, it would go up to nearly 15v, and then down to 14.82v.

Going off suggestions here, the CEM was removed and inspected. All seems good connectors wise and no corrosion, but two of the fuses: 45,57 had blown.
Tried changing these to see what would happen - no real change.


Not sure what to do now, any help is appreciated.


So a little update.

I got one of the better diagnostic scanners and gave it ago (icarsoft - still **** but better than nothing). I had left the car for a while and this time it started just fine and after a minute the brake failure, anti-skit faults came back. Revs went to 0, limp mode, etc.
The scanner shows many loss of communication faults such as to the steering angle sensor, CEM, ABS, etc.
The scanner has the ability to scan the CEM and a CEM-low (what are these two?). CEM-low shows something about the main battery relay, general electric fault. While the CEM won't let me scan. Is that a sign of anything perhaps? Red herring?

The voltage on the scanner (which must read from the computer) flickers through a range of values quickly but generally shows 13-16v. I would try the voltmeter again today (a few days later), but since fiddling around the battery has dropped to 10v and requires a jump start to get going. And I'm kinda done messing around with it.
Every time it's left for a while, it will let you start up and move off for a couple of meters or more and then remember the fault. Sometimes then it'll prevent you from starting or not.

At this point, not sure what to do. Not sure who I trust can fix it without being a money pit.
Advice as always appreciated

[pinballdave]

The CEM on P1 Volvos is actually two separate computers in one box. One that talks to the ECUs on the low-speed CAN bus, and another one on the high-speed CAN bus.

The Volvo VIDA diagnostics treats both as a single ECU, but on some third party scanners you need to scan both CEM-H for the high-speed one, and CEM-L. It sounds like there may be communication errors on one or both CAN buses.

Your symptoms can be caused by a failing alternator, or a worn out battery. I'd get the battery tested as a first step.

The charging systems on these cars are complicated, as the output of the alternator is controlled by one of the cars ECUs, and which ECU depends on the car year and the engine size/type. So we'd need to know which model you've got for more relevant advice.

If you can list the fault codes you're reading, then this might be able to narrow down the areas that need to be checked. Ideally a scan with Volvo's VIDA/DICE, but if the icarsoft is the Volvo specific version, then it should give good enough results to be useful.

[hughjass]

ah, can't believe I forgot to mention, it's a 2012 Volvo V50 1.6d.

So, it's the volvo icarsoft one, it says there's a link error when I try to scan the CEM (non-low). I can't clear its codes nor read them, but I can read its part number.

I can use software and a voltmeter, so is there a way to test an alternator/battery with my skillset, or ask have to ask a mechanic friend? I remember now that when running off both the battery or when the engine is on, the radio's backlight flickers a bit.


Here are some of the codes I took photos of, might've been between different runs/days:

U012600 - Lost communication with steering angle sensor module, general failure information.
U014000 - Lost communication with central electronic module, general failure information, etc.
C110964 - Vehicle dynamics control switch. Algorithm based failures. signal plausibility failure.
P170181 - Reverse engagement error, bus signal / message failures. Invalid serial data received.
U042841 - Invalid data received from steering angle sensor module, system internal failures, general checksum failure.
U000188 - High speed CAN communication bus. Bug signal / message failures. Bus off <-- seems highly relevant?
U0121 - Lost communication with anti-lock brake system..
U012100 - Lost communication with brake control module. General failure information.
U041500 - Invalid data received from anti-lock brake system (ABS) control module. General failure information.
B139F12 - Main battery relay. General electrical failures, circuit short to battery.
1B02 - Main battery relay. General electrical failures.

I have a bunch more from the initial scan before I cleared and ran it a few more times later on, but I think that's enough

Learning about the volvo diagnostics for the first time, I can try to get this vida software to work if that'll get better diagnostics. But can I use a generic J2534 ond, or must I get a DICE unit, time to research...

[hughjass]

Originally Posted by pinballdave

The CEM on P1 Volvos is actually two separate computers in one box. One that talks to the ECUs on the low-speed CAN bus, and another one on the high-speed CAN bus.

The Volvo VIDA diagnostics treats both as a single ECU, but on some third party scanners you need to scan both CEM-H for the high-speed one, and CEM-L. It sounds like there may be communication errors on one or both CAN buses.

Your symptoms can be caused by a failing alternator, or a worn out battery. I'd get the battery tested as a first step.

The charging systems on these cars are complicated, as the output of the alternator is controlled by one of the cars ECUs, and which ECU depends on the car year and the engine size/type. So we'd need to know which model you've got for more relevant advice.

If you can list the fault codes you're reading, then this might be able to narrow down the areas that need to be checked. Ideally a scan with Volvo's VIDA/DICE, but if the icarsoft is the Volvo specific version, then it should give good enough results to be useful.

Got VIDA installed, but no good cable. Can't find a reasonably priced DICE unit around. Anyway, are the above faults in the previous post a good enough starting point, or do I need to get a DICE module to be sure..

[pinballdave]

If your cable is J2534-2 (that can communicate with both CAN buses), then it should work with VIDA, providing you have decent up to date drivers for the cable.

If your cable is the older J2534 or J2534-1 then it can only communicate with a single CAN bus, and will not be suitable for these cars.

The main benefit of VIDA is that each fault code can be looked up, and it gives more accurate descriptions of the possible causes of the failure. Whereas with a generic code reader, you only get the generic description, and it's harder to determine whether there is likely to be one common cause.

However given that most of your communication faults appear to be on the HS CAN bus, I'd start by checking that one out. Remove the car battery, and measure the resistance between the pins of the CAN bus, you should read about 60 ohms if you read 120 ohms, then there is likely to be a break in the wiring somewhere. It's also worth tapping the connectors, and flexing the wiring loom while you make this measurement to see if there are any loose connections.

[hughjass]

Originally Posted by pinballdave

If your cable is J2534-2 (that can communicate with both CAN buses), then it should work with VIDA, providing you have decent up to date drivers for the cable.

If your cable is the older J2534 or J2534-1 then it can only communicate with a single CAN bus, and will not be suitable for these cars.

The main benefit of VIDA is that each fault code can be looked up, and it gives more accurate descriptions of the possible causes of the failure. Whereas with a generic code reader, you only get the generic description, and it's harder to determine whether there is likely to be one common cause.

However given that most of your communication faults appear to be on the HS CAN bus, I'd start by checking that one out. Remove the car battery, and measure the resistance between the pins of the CAN bus, you should read about 60 ohms if you read 120 ohms, then there is likely to be a break in the wiring somewhere. It's also worth tapping the connectors, and flexing the wiring loom while you make this measurement to see if there are any loose connections.

I get 60ohms from the obd port at 6,14.

I read another post about checking the voltages from these to the two grounds. My multimeter doesn't quite fit in the obd port so I had to wedge something in and I can't seem to get a reading or all 4 combinations are 0v. The ports 6,14 are tight, but 4,5 are looser and my metal wedge doesn't seem to be making contact as it can move around. If that makes any sense.

[Teddy1975]

Loan a proper battery tester or take the battery to someone who has one, a volt/multi meter just isn't made for testing car batteries. How old is the battery?

[hughjass]

Originally Posted by Teddy1975

Loan a proper battery tester or take the battery to someone who has one, a volt/multi meter just isn't made for testing car batteries. How old is the battery?

Can it be the battery if it's high speed only faults and if it's the same when jumped to another car and started?

Anyway, looking now for a person to tow it to..

[hughjass]

Originally Posted by pinballdave

If your cable is J2534-2 (that can communicate with both CAN buses), then it should work with VIDA, providing you have decent up to date drivers for the cable.

If your cable is the older J2534 or J2534-1 then it can only communicate with a single CAN bus, and will not be suitable for these cars.

The main benefit of VIDA is that each fault code can be looked up, and it gives more accurate descriptions of the possible causes of the failure. Whereas with a generic code reader, you only get the generic description, and it's harder to determine whether there is likely to be one common cause.

However given that most of your communication faults appear to be on the HS CAN bus, I'd start by checking that one out. Remove the car battery, and measure the resistance between the pins of the CAN bus, you should read about 60 ohms if you read 120 ohms, then there is likely to be a break in the wiring somewhere. It's also worth tapping the connectors, and flexing the wiring loom while you make this measurement to see if there are any loose connections.

Any chance you can link me this right cable? All I find on eBay is MINI VC for Toyota..

[Simmy]

serch out mat leavsley he can supply you with either dice or mongoose cable the units he has are all tested an will work unlike the chinese untested ones. vvedinfo 1097 is his ebay sellers adress Get a known good car battery as a starting point or you may struggle as dice unit is power hungry