'98 V70 Lights on Dash flicker w/ revs.

Post by **E Showell** » 04 Mar 2014, 07:12

I noticed at idle at a stoplight the other evening that the dash lights seemed to fade/increase in intensity in relation to engine idle. If the idle dipped a bit, the dash lights dimmed. If it came up, they brightened -- not talking huge variations in brightness. In fact, if you weren't looking for it specifically, you probably wouldn't even notice it. The idle wasn't fluctuating enought to even register significantly on the tac. I still have my original alternator at 263K miles. Are the fluctuating dash lights a precursor to alternator failure?

Post by **erikv11** » 04 Mar 2014, 07:55

Flickering lights are are a classic sign of worn out brushes. You can change the VR in your car with the alternator in place, be sure to check the slip ring too, though. Several alternator posts today, check out the top of the forum.

I would also check the grounds and both ends of the positive cables.

Post by **E Showell** » 04 Mar 2014, 08:18

VR? I am assuming "voltage regulator"?

Post by **erikv11** » 04 Mar 2014, 08:23

Yessir, voltage regulator.

Check this out too: https://www.matthewsvolvosite.com/forums ... =1&t=61610

Post by **cn90** » 04 Mar 2014, 08:35

Many many years ago, the VR is a separate component from the brushes.
Fast forward to the modern time (1990s --->), whenever the word "VR" is mentioned, it is implicitly understood that it contains both the VR and the brushes.
For the record, the VR and the brushes perform different functions, but for the sake of simplicity of maintenance, the modern VR contains both the VR and the brushes.

Post by **E Showell** » 04 Mar 2014, 16:18

How long should an alternator go for? I'm guessing I'm on the original at 263 K miles.

Post by **cn90** » 04 Mar 2014, 20:43

Alternators can die different ways:
- Worn brushes around 200K+.
- VR can go out any time, even when it is 1-2 years old, but the general consensus is about 130K-200K range.
- The windings (copper) seem solid but they can break and/or short-circuit with time/mileage.

At 263K, if this is original alternator, it is overdue.

Post by **E Showell** » 04 Mar 2014, 20:59

Tested this evening at local auto parts retailer. Specs as follows:

Battery voltage: 12.44

Measured: 520 CCA

Rated: 500 CCA

Temperature: 46 degrees F

Starter

Cranking normal

Voltage 11.26V

0.0 amps

Time: 6.00 sec.

Charging system:

No load: 12.92V

Loaded: 13.34V

Within spec?

Post by **erikv11** » 04 Mar 2014, 21:49

Battery resting voltage is within spec.

Voltage when cranking (11.26 V) I don't know about, never tested that.

For the charging system, the numbers seem a little low. On my cars, when I turn them on and then check the voltage at the battery it is always above 14, like 14.4 volts. However I have read that with all the electrical stuff on, that may drop to about 13 (but no lower).

You can get a very good look at the state of the brushes and the slip ring with the alternator still in the car, just pop off the black plastic cover (3 screws then some snap tabs).

Post by **jblackburn** » 04 Mar 2014, 23:04

I agree, your alternator output numbers look low. Should be 14+ unloaded; high 13's loaded.

My brushes were worn back around 180K...the interior lights flickered a little bit at idle...and it finally gave up the ghost in the 220's.