Initially posted on Volvo Chat Forum/Transferred here.....SORRY

I'm not new here, as I get most of my repair info here. GREAT site with great ideas and how-to's!!! This is however my first post. Usually very good at reading and fixing. This issue is giving me fits.

Back Ground Info.
99 volvo S80
68, 700 Miles (belonged to an older man, kept in his garage, and barely driven)
General maintenance with exception of ETM replacement about a year ago.
A few upgrades: CAI, Plugs (platinum 2 from Bosh), Silicone Vacuum hoses, Fuel line and new fuel filter.
Great car so far.

3 weeks ago while coming home for t-ball practice with my son, and without warning mind you, I see a message on my DIM "EL SYSTEM SERVICE REQUIRED". Within about 2 miles, when I "TRY" to pull away from a red light, no go. RPM's at 1000, muffler crackling noise, moving about 1/3 of a MPH. A good samaritian helps me to the median. I tow it home and troubleshoot. Here's what I've done:

1. Checked the battery terminals - clean, but I pulled and cleaned anyway with wire brush and small file (did this for all connectors mentioned below also).
2. Checked the power cables from the battery to the Alternator and voltage regulator - I noticed the single cable running from the wiring harness to the alternator/voltage regulators plastic housing was split and broken, I fixed it, then pulled and cleaned the other connections.
3. I re-routed the B+ cable from the mount by the sway bar as shown in VADIS as a "possible" electrical fix for certain symptoms (none of which I seem to have with my current situation), did it anyway to eliminate any doubt
4. Checked all the grounds (Engine compartment and trunk by battery) - The one from the tranny to the underside of the air box was loose at the tranny (airbox doesn't exist due to a new air intake installed a year or so ago). I pulled all grounds and cleaned, bought a new negative battery cable and installed.
5. Charged the battery overnight
6. Checked the voltage at the battery with the car off and it was 14.47
7. Checked the voltage with the car running (lights, heater, radio on) at the battery, it was 14.45, then checked at the alternator, it was slowly but surely dropping from 14.38 down to 14.04 within aout 2 minutes.
8. Took it to Autozone and Pepboys, both of which say there is no electrical issues found.
9. The serpentine belt is tight an no other components are having issues that I can tell so far, although I don't hear anything coming from the alternator, no sounds to indicate bad bearing or diode

However, just as many have posted, I drive it for a couple of hours, and BAM, DEAD. Left stranded.

I'm good at fixing issues with my volvo, but what do I fix if no one can seem to find any issues? I've searched the forums and done everything stated with the exception of replacing parts, money is tight so if someone can point me in the right direction I would be GREATFUL!!

 

It sounds like your alternator or voltage regulator may be going bad, thus explaining the slow drop in voltage.

Not a Volvo, but 1st Gen Nissan Altima's were known to have bad voltage regulators in their Alternators (single piece unit design) where cars would run fine for a while, but after driving for a bit, they would lose power, dash lights would illuminate and the car would eventually stall out. An intermittent voltage regular/alternator failure due to heat wouldn't be picked up on at PepBoys or similar who just test load output unless you brought it to them when it was happening.