00 S70 ETS, ABS, Brake light - SOLVED Topic is solved

[deardeergod]

It's been almost 7 months of frustration, but I can finally say it's over.

It started when I was rolling down the highway just like any other day when the car gave a lurch, a small thunk, but was still running. I looked at my dash to see the ETS, ABS, and brake light on, and my speedometer, tachometer, and odometer at zero. The car was in limp mode and I took the nearest exit ramp. I pulled off to the side and restarted but there was no change. Fearing I would damage the vehicle I called a tow and took it to my mechanic. Even more surprising was when it got to my mechanic all the faults were clear, all the gauges were back, and it ran just fine. They kept the car for a few days but weren't able to reproduce anything so they handed it back to me.

Only a few days went by when the car pulled its stunt again producing all the same faults as before. It was back to the mechanic where they said it was most likely the electronic throttle control and at just over 125,000 miles it seemed plausible. Nearly $1000 later and I had my car back when a few days later it faulted again. Back to the mechanic it goes. They talked to Volvo and Volvo recommended replacing the brake booster diaphragm position sensor but that didn't solve the cars woes. Everyone was scratching their heads.

There didn't seem to be anything to replicate these faults, it wasn't when going a certain speed, turning, after a certain amount of time driving, anything. Everything would be fine until it suddenly wasn't and there would be a sharp but short acceleration, the dash would light up, I would lose my gauges, the transmission would go into limp mode, and the engine would "search" at idle. After being turned off for about 30 minutes, the car would be right as rain on restart. This whole faulting nonsense would happen every other day, sometimes every day, and I drove the car for months like this. I bought my own OBDII adapter and read the codes myself, unfortunately none of my research helped. The only thing I was able to pin down during those months was that the car would sometimes fault during a gear change going up a hill or after sitting out in the sun for awhile, which didn't make much sense. One other thing I took note of was the throttle body would beep for an extended period of time (about 2 minutes) while doing its alignment after shutting the car off after it faulted.

The car did not like errand hopping in its compromised condition, but sometimes I would have to. One day after it faulted a few times the upwards arrow starting flashing on my dash and I assumed the transmission was giving up the ghost. The car still ran the same as normal, so I drove it to my mechanic. They had it for a week and did numerous tests on the transmission solenoid and checked to see if there was a voltage drop when the car faulted. They couldn't find anything conclusive but thought the car had some issues restarting after a fault so they switched out the battery.

Who would have thought that would have been it. The battery was the problem. I've had the car back for over a month and it has been perfect. It doesn't make any sense to me but hey I'll take it. I hope you enjoyed this read and maybe keep it in your back pocket when you hear about a car with ridiculous symptoms such as mine was having.

[polskamafia mjl]

Yes these cars are very sensitive to battery voltage and when it isn't correct lots of weird things start to happen. Glad you got it figured out.

[EstVolvo]

Give it some more time.
Have you ever replaced the ABS module?

[deardeergod]

I have not replaced the ABS module, when the car first started giving me grief that was the first thing I found when I started looking up the symptoms. However, all the fault codes pointed to the throttle system.