Hello
I have a Volvo S40 2.0T 1999.
I have it since 2007, and never had any problems...until last year.
Started with heated oxigen 2 sensor fault. At beggining was an intermittent fault, now it's steady. But the only symptoms was a little
higher consumption of fuel.
In April was time to replace the timing belt. a month later had to replace the alternator. the mecanic did not changed the bearings when timing belt replacement .
In Jully the idle started to have problem, the car went off
constantly.
The last one, car don't get start. No starter motor. Only i hear is something clicking...a rele one.
So I changed battery. The old one went to 9v. and was the original one. but with the new battery hapened the same. this time the battery have 7v.
I check the fuses, all good.
So....
I cleaned the idle air control, before i try the other battery.
The second was not a brand new battery, was in my other car. I used only to test the idle problem.
I have all the electric schemes from autodata. The problem is i dont know where is the location of some componets.
last 3 days i spend the time looking in net to know the location. no luck.
For exemple...where the hell are the ECU??? not in motor compartiment for sure.
Now I'm thinking to call a mecanic to read the ecu for codes. don't want to risk a new battery by trying started the car after performing all the tests.
I'm far way from any city, and there isnt an electric expert around here. I'm an electronic man...but worked only in airplanes and telecomunications..not in cars.
I send foto from motor's compartiment....never found any foto that looks like my car.
This car came to portugal via Sweden embassy, so i think this model never was sold is Portugal.
anyone can help me? please!

 

wow all over the map... best is to break down by problem area:

Starting: What happens if jumper the car with a 2nd vehicle? Have you cleaned the battery terminals/checked the cables to ground and to the starter? do you get voltage to the starter through the power cable? Does the battery drain when the car is off (measure current flow).

Alternator: did you install a new/rebuilt or used replacement part? Did you check connections? If the car can start with a jump, check voltage at battery at idle (should be 14V+, under load (lights, blower, rear defroster etc) should stay over 13.5). If its over 15V you may be overcharging the battery thus damaging it..

Engine performance: Pull OBD2 codes. You should be able to get a reader and just need to get a full 12V battery connection to read the codes - the engine shouldn't need to be on. You read from the OBD2 port not the ECU. I'm pretty sure your ECU is in the center console accessible by removing the sides, but there's no reason to access it (they rarely fail). Its possible you need a new O2 sensor (codes will help) but also inspect for vacuum leaks/torn or out of place tubes.

 

The alternator is new, and it was not me who installled..it was a mechanic. didnīt check it....but i will, when i will be able to turn on car. The second car, well, i tried its battery in volvo, and battery died (7v), didnīt jump because i did not have cables. Did the same as the original battery, only a permanent sound of clicking, that looks like from a rele.
never had starting problem, just turn the key and started at 1š clik. I drived almost 200km in day before, no problem (except idle), in morning it happened at 1š attempt. It rained all nigth
the battery connections are good, and ground is good, max 0,006 ohms, but i only checked negative to the chassis, and its infinte positive/chassis.
I'm looking for cables to jump cars.

I want acess to ECU to test the O2 sensor, because i dont know where the O2 sensor cable is connected, and maybe it's near ECU since the code tells that is the rear O2. the front one is in motor compartiment.
For now just need powered the car, and check all, try start the car, check all. So I need to know exactly what, where and how to check.

Tks for your reply, i will do what you told, when possible

 

the o2 sensor doesn't plug direct into the ECU - you should be able to trace the cable from the sensor up to its connector (as if you were going to replace the sensor). Keep in mind when you get OBD2 codes they may be general faults. For example, your O2 sensor can report going out of range - which may be due to its inability to compensate for a vacuum leak. So first thing is to check for vacuum leaks, torn hoses etc, check for air leaks around the intake (by the MAF, throttle body, intake air valve. Note if your battery is only measuring 7 or 9 volts, it won't spin the starter motor - as you heard, all you may get is a solenoid click.