Xsara Picasso 04 - Fob/Immo/Issues

[magictorch]

Hi I am looking for some pointers on running down an electrical issue with our Xsara Picasso 90Hp 2.0 HDI on a 2004 plate.
Symptoms.
Phase one:
- Air bag warning notice started on console. Difficult to see as the bulbs had gone. I have now replaced these.
- I plugged in radio that had been removed and think that I plugged the radio harness in the wrong way round. I was in a rush. Harness now removed.

Phase two:
- Remote stops working on key fob and then immobiliser warning notice on console.

Change management: I change the battery in key fob. I go through the BSI reset process to no avail.

Phase three:
- Battery goes flat and then economy mode notice is displayed on console.
- Console displays battery warning light. No matter which battery I put on her.

Change management: I now try three batteries. No change. The car was recently garaged and had the air con pump changed for a 2nd hand one as the bearings were going on the last part.

Please can I have some advice on where to start?
Thanks in advance.

[wurlycorner]

If your battery is going flat (and it’s a known good one/has been replaced) then either the alternator is not charging and/or you have a parasitic drain.
Once the battery has dropped below a certain level, economy mode will be triggered.
Low battery can cause other electrical gremlins, so it’s sensible to start there.

A few basics to check if it’s charging:
With the battery fully charged, does the battery light on the instrument binnacle illuminate when you turn the ignition on and then go off when you start the engine?
Do you have a voltmeter? If so, with it set to DC volts, put it across the battery positive and negative terminals. Should be around 12v with a fully charged battery (engine off) and around 14v with the engine running. What do you get?

Once we’ve confirmed if it’s charging ok, then can consider parasitic draw (the unplugged stereo might be a clue that someone was already looking into this…) but it’s less easy/more time consuming to track down a parasitic draw, so let’s start with charging first.

[magictorch]

I have ensured the battery is fully charged. Battery is approx. 3-4 years old.
Voltmeter is reading 12.56.
When attaching the charged battery the battery light on the console stays on. I waited (edited for grammar)15minutes to see if this would reset but it did not.

Regarding the radio. It was me who had taken that out. I was stripping the car down of useful things as the (garage) diagnosed issue was not the camshaft gear but something on the aux side. Thus the swap of the AC pump.
Thank you for your suggestions

[wheeler]

So is the car starting currently or not?
If not i would guess you have popped the fuse that supplies power to the Com2000.
Also the battery light will not go out till the engine is running, confusingly the battery lamp has nothing to do with the battery condition, if the battery lamp is on this is to warn you that the battery is not being charged, so if the engine is not running the battery is not being charged.

Once the battery has dropped below a certain level, economy mode will be triggered.

That's not actually correct on this vehicle, its too early to have battery monitoring. Eco mode is triggered purely by a timer, it does not monitor the battery voltage, condition or current draw.

[magictorch]

The car is non-runner. Which fuse is the Com2000 please? Engine bay or interior.
Noted on the battery light. I will ignore that for now.
Thanks for your suggestions

[magictorch]

An observation. When connecting battery and moving key to ignition sequence there is an audible click. Temporary nudge of wiper arm. The sidelight is illuminated on the cluster as well as oil, water engine mgmt (K).

[wheeler]

Will be inside on the BSI
Check fuses 4 & 15 particularly if they are OK check all the fuses

[magictorch]

I have checked all fuses in BSI. Observation checks show no blown fuses. I did not test each fuse for continuity.

[magictorch]

Observation. The com2000 unit did have a fault on the indicator stalk for some time whereby indicator sequence and side lights would intermittently fail. For example when headlights were on the indicator left would not work. This seemed more to do with contacts in the com2000 than electrics.

[wheeler]

Do you have 12v at both sides of fuse 4 in the BSI?
Don't rely on a visual check.

[magictorch]

With battery connected and key ignition turned on.
I tested voltage across the terminals of fuse 4 of the BSI. There was no reading at all.
Am i testing this wrong?

[Paul-R]

Yes. If you were reading a voltage it would mean that the fuse was blown and that whatever the fuse was feeding was switched on and trying to get power to operate.

What you need to do is put one of the multimeter leads to an earth point and then see if there's voltage on each side of the fuse. It doesn't matter if you put the red lead to earth instead of the black, the meter reading will just indicate a negative voltage instead of positive - assuming there is voltage there of course.

If there's voltage on on side of the fuse and not on the other take the fuse out to see if it's blown. Sometimes the fuse is OK and just needs reseating.

[magictorch]

Noted. I tested the fuse for continuity with the tester and it was fine. I will test for voltage across the terminals as described and report back.

[Paul-R]

If the fuse is fine then, unless there's something bizarre going on with the fuse holder, you won't get a voltage across it. As I said you need to see if there's a voltage from either end of the fuse (shouldn't matter which if it's not blown) against earth.

[magictorch]

Thanks I understand now. Fuse 4 must be in place. Check off voltage of 12v from the top of the fuse to an earth.
Thanks for your help