Dash Lights Come on then Off - Car drives fine (96 850)

ryanmcgrim · Post by **ryanmcgrim** » 09 Dec 2016, 07:51

I have a 96 850 Base NA that seems to be running perfectly, but last night coming home, all of the dash warning lights came on at the same time, then a few seconds later came off again. It happened once more. It did not seem to be related to anything. I believe I was accelerating from a stop sign the first time.

I put a multimeter on the battery with the car off and it came back with 12.5 volts with a flicker to 12.6 once, but mainly stayed on 12.5.

I started the car with the lights, fan and defroster OFF and got a reading of 13.8v.

I turned on the lights, defroster, heat, radio, and with the car running was getting a reading of 13.4 volts.

I drove the car to work today (hour+ drive) to keep an eye on it and the light issue did not occur (they stayed off the entire time).

I've got a 2+ hour drive this weekend and no other transportation so I guess I'm just hoping for some advice on whether I can take it and be mindful of voltage, or not.

Then what my order of operations would be to diagnose this issue.

I have heard that the lights can come on like that when there is a spike or droppoff of voltage to the system, and that most likely would mean the Voltage Regulator, or could be the alternator. Other ideas is that it could be a bad ground somewhere in the dash or main terminals / the b+ terminal. Yet another Idea could be that it is a faulty ignition switch. I wiggled the keys on my way in to see if I could cause the issue to happen, but no luck, and the key seemed pretty secure.

Could someone chime in with some wisdom on what they would do in this situation? I have a battery charger if need be, and am thinking of getting a portable jump pack for this trip as insurance, but regardless need to figure out the order of operations to get to the bottom of this eventually even if it makes it. Thanks so much everyone!

ryanmcgrim · Post by **ryanmcgrim** » 09 Dec 2016, 07:58

Also wanted to mention that EEuroparts has a Bosch voltage regulator for $35, would getting this and swapping it out be a good cheap way to see if it's the voltage regulator, or is there an easy test to do with the multimeter to rule it out first? Thanks again

Post by **scot850** » 09 Dec 2016, 09:27

Depending on the age of the alternator, then it would be good preventative maintenance to replace the regulator for this time of year where it gets loaded higher.

Battery sounds ok. Is it one where you can open the cell top and see the level of the electrolyte? If you can, open and check they are to the level. Most batteries have a lip or level marker in the cell.

I think the more likely may be the ignition switch electrical portion may be failing.

Finally check all the battery cables for corrosion and earth cables for good contacts.

Neil.

ryanmcgrim · Post by **ryanmcgrim** » 09 Dec 2016, 11:27

Thanks for the info Neil. I believe the battery is sealed. It sounds like I should go ahead and order the Voltage Regulator to see if that makes a difference. Is there a way to test the ignition switch at all, or should I also just order one and replace it? Is junkyard OK or do I have to spring for new?

Seeing as none of these parts can be procured today, do you think it's much of a risk to take it on this trip (4 hours RT) or am I really asking for it? I guess I'm asking is do ignition coils tend to take a while to completely die and would that prevent me from driving it? ALso if it is the Voltage Regulator, is that also a sudden death thing, or given the fact that this was thre first time this happened and has been fine the last 2 hours of driving is there a good chance the issue will creep up a few more times before giving out completely?

Thanks so much!

Post by **sleddriver** » 09 Dec 2016, 11:57

Given your vehicles age and the fact you live in Boston, I'd check and clean every engine/major ground point. Also check the wiring/lug connections for corrosion. An electrical schematic will show you where all of these are located.

ryanmcgrim · Post by **ryanmcgrim** » 09 Dec 2016, 13:00

Thanks sleddriver, I will do that when I get home tonight. I actually have another puzzling development. I just took the car to grab some lunch. Started and drove fine. I also had an errand to run, so I started and stopped it a total of 3 times, with no problems whatsoever. I got home and decided to take some more multileter readings and perhaps resistance to ground readings on some of the wires / connections you are talking about.

First, I checked voltage at battery with car off.

Now I'm getting 12. 1v

Last night and this morning when I got to work, the battery with the car off was reading 12.5-12.6

I kept the leads connected and started the car. While the car was turning and starting the volts dropped in the 10s as expected, but it still took like 4 full seconds of running before the volts returned to 13.8V. I put on the defroster and it dropped to 13.6, then fan it dropped to 13.5 then lights and it ended up at 13.4. If I turned off those things it would immediately jump back to 13.8.

Now I'm really confused. Is my battery bad? Id my alternator being finnicky in that it took 3-4 seconds to put out 13.8 volts? I'm starting to get worried about this trip now even though the car is starting and running well. Does this information provide any more of a clue as to what is going on?

Jaguar xjs · Post by **Jaguar xjs** » 09 Dec 2016, 13:33

I'd drive down to autozone or advance and have them run a charging test on the car. I had it done a couple days after I bought the car and noticed some sketchy numbers.

I cleaned a bunch of grounds and hot leads under the hood and returned for another test with all positive results.

Gordon

ryanmcgrim · Post by **ryanmcgrim** » 09 Dec 2016, 15:38

I know they aren't really reliable, but I'll head down there on my way home from work, assuming it gets me there!

ryanmcgrim · Post by **ryanmcgrim** » 10 Dec 2016, 05:53

Well that wasn't helpful. The auto parts guys actually got in a big argument on what my problem was, and what part to buy. They hooked up their charging system tested and it came back with good battery but very low. Alternator charging at 13.4 with load but bad voltage regulator. One guy said it was definitely the battery, because the alternator was putting out even voltage with no spiking. The other guy said he was a moron and it clearly said bad voltmeter. Now I don't know what to do. I'm thinking about just keeping a jump pack on my car and hooking up a volt gauge to the cigarette lighter to constantly monitor voltage for a while until I figure it out.

If the alternator is charging, all lights, headlights and starting strong. Why is the battery at 12.1_12.2 volts? Bad battery? How accurate is the charging system tested for diagnosing voltage regulators. Any idea how to determine which regulator to get without removing alternator from car?

Post by **MrPc** » 10 Dec 2016, 12:33

scot850 said:

Finally check all the battery cables for corrosion and earth cables for good contacts.

This.

Are you measuring voltage across the battery terminals? If you are, then I suggest you do a voltage drop test across your positive battery cable. You can search on this, but basically you just put the + probe on the alternator positive terminal, and the - probe on the positive battery post. Do this with the lights/fan on and off. Also check what voltage the alternator is putting out under the same conditions, by checking the voltage at the alternator positive terminal. When we know what voltage the alternator is putting out and how much of it is lost across the positive battery cable we'll be in a better position to know what to do.

I think the readings you have now point to resistance in the cable because you're seeing the voltage drop as you draw more current. Your battery voltage is low, and so is the charging voltage. So your battery isn't receiving a full charge, especially when you have additional electrical load to the alternator.

The connection between the positive battery clamp and the cable tends to go bad in these cars. There are a lot of threads on this. The remedy is to fix or replace the cable. Replacement cables are available at FCP & IPD etc.
jreed and others have made their own replacement: https://www.matthewsvolvosite.com/forums ... =1&t=61747
Or you can repair your current cable, which is what I did: https://www.matthewsvolvosite.com/forums ... =1&t=60223
I think rspi has a video on this too.

Whew. Now, after having said all that, I don't think your low battery is what caused your dash lights to flash. My only experience with a low battery flashing dash lights was when the battery was very very low, much worse than yours.

scot850 also said:

I think the more likely may be the ignition switch electrical portion may be failing.

I would look at this. Try wiggling the key with the car running and see if you can get the lights to blink.

Paul