Electrical Gremlins
 

Hi all, I put 2 new batteries in my car recently main and aux. The car ran flawlessly for 2 days including a 150 mile round trip to Derbyshire and back. It was then left unused outside my house for 2 days. The next time I tried to use the car I got 10 yards down the road and noticed I had no Rev counter or speedo.

In short, and only while the engine is running, the car will throw all sorts of warning lights including brakes, srs airbag, coolant system and others. The engine starts/runs fine, pas, brakes and handbrake. Indicators work but no clicking noise and flashing arrow on the console to tell me it is on. The radio and ac and anything else on the centre console only works intermittently, as do the electric windows. For a couple of minutes the car will run fine, then the warnings will come back and the speedo etc go to 0. The radio almost never works unless the engine is off, then it runs fine. Unfortunately, the stop/start function is now working fine!

I'm tempted to hand it to an auto electrician rather than my local Volvo specialist who wanted to charge me £102 just for a scan.

Any ideas? Sorry for such a wall of text on a first post but this has me tearing my hair out. I've read through over 240 pages of this forum and many on others and couldn't find a definite solution. I don't want to give it to a garage who may start throwing parts at it when it is just an electrical error somewhere!

start by checking battery connections and earth are all good and tight also check for any water ingress on to the cem if your car has the battery monitoring system did you re set it. and have you fitted the correct type of battery's for your model of car look for a forum member near you who had vida or other good diagnostics.

Would there be a problem if the original battery was an efb and the new one is an agm? There is no sticker on the old one that indicates its type. I have checked voltages on the new one and it looks fine. 12.8v resting, 12.3v when connected to the car, doesn't drop below 10v when starting and is at just under 15v when the engine is on. There is a small amount of water in the passenger footwell but the cem looks okay. I reset the bms using the button push method on this forum and also disconnected the bms cable for 30 mins.

I might try fully recharging the old battery and connecting it in place of the new one, the only problem with the old one was poor starting.

yes try the old battery back on and clear all codes and warning messages to to see if the problem still exists if the problem dose not return it may be the battery that is causing problems