Hey so i bought a volvo 850 2lt turbo. The service light was on but it was fine it disappeared after 2 mins like it should. It was boosting fine until randomly when driving the service turned off at the 2 min interval but then all of a sudden all the warning lights came on and stayed on. When I turned off the car half the warning lights stayed such as parking brake light fuel light and and few others like coolant and the car has been running alright but lost of power . Any ideas ?

 

Check your voltage - with the engine running and without. Once when my alternator went I got some similar behavior - but the car ran until the battery ran down - went into limp then died (2 miles from the dealer... at least I got a free tow). Next is to check for codes and reset the service indicator light... What year is the 850?

 

It's a 1996 model.

 

Is it OK to drive in this mode ? I heard it's like limp mode or something . How do I check for voltage ?am I checking voltage on battery or alternator ?

 

The quick test is to use a volt/ohm meter (VOM) to measure voltage from the battery terminals. Start by setting the VOM to DC Volts with a range of 20 volts. With the engine and ignition off, put the black probe on the negative then red to positive. You should see 12.6V for the battery. Now start the car and let it idle. Measure again and you should see something between 14.2 and 14.7 V. If not - your not getting a full output to the system. Finally add an electric load by turning on all the lights (high beam), AC Fan on high, rear defroster on, radio on etc. You should see the volts go down - typically between 13 and 14. If you see the voltage go below 12, then I'd suspect the alternator or a connection that's not allowing full current. Using the easy to difficult approach, clean the battery terminals and retighten to ensure a good connection, then inspect the larger connections to the block (negative ground strap).

As to the issue with driving in limp mode from a bad battery or alternator, eventually the car will drain the battery...if its an alternator issue, you don't want to add another $125 for a new battery which can happen if it gets totally drained. So if you want to drive a few miles to the shop, charge the battery if you can first, but I wouldn't plan on commuting out the week.

Last thought - since you have a 96, you can also check for any engine codes without an OBD2 unit. This is done via the diagnostic ports on the left front side. Look around for a post or a youtube vid on how to use the test probe and LED read out.

 

This is a strange feature of these cars. The warning light 'test' mode depends only on voltage. when the voltage is low, the instrument cluster assumes the engine is not running, and it says hey, it's time for the ol' warning light christmas tree test.

Naturally, it does make battery problems a bit strange to diagnose....

 

Hey so I think there may be a problem with the battery as the tonight while driving home the lights came on again. and as I was near my house my radio turned of, the dash stopped working and all the electronics one by one was turning off and the car was losing power. eventually i pulled over near my house and as soon as i put it in park. it died. I'm thinking it may be the alternator now as I got the battery tested and it appeared fine. Do you know if any other model volvo alternators fit the 850 as parts are hard to find here in New Zealand.

 

I agree with your diagnosis. The battery is running down because the alternator went out.

Most of the time, you can get by with replacing the voltage regulator + brushes assembly, which is tiny. If you can find a source for that, you could have it mailed to you. It's about the weight of a golf ball. They're about $100 to $150 US at auto part stores, though. not cheap.

 

Bad alternator. Most of the alternators will work find from '94 through '98. You may also try replacing the regulator, nice cheap fix.

 

There's a s40 1997 1. 8 lt car at the wreckers. Will the alternator fit from that?

 

If you look at Rockauto.com's catalog it looks like the 97 S40 1.9 and the 96 850 2.0T do in fact share the same alternator part number. Just note that the S40s came with an 80A alternator and the 850s came with 80A and 100A so best to match up by your car's alternator part number (the OEM# should be on a small plate). Best to do a bit of research as those models never came to the US (so not a lot to go by from here).

A good plan would be to install the S40 and see if it works, then get a rebuild kit for the original. Based on your comments it sounds like the voltage regulator which can be repaired as shown in RSPI's post.