99 S70 GLT Electrical Issues

Slumbo · Post by **Slumbo** » 10 Sep 2014, 07:03

Hi. This is my first post. I've owned my S70 for 12 years, and I love the car, but I need to get it running properly or get rid of it. It has several issues, but I suspect that many of them may be results of one electrical issue. I just don't know what it may be. All of the car's electronics seem to be getting barely enough juice to function.

Symptoms;
-Very dim headlights. I must drive with the brights on just to tell they're on.
-power windows are getting SLOW.
-all lights get dim any time I use power seats, windows, etc.
-clicking noise behind center vents. I've read this may be the motor not having enough power to open/close airways.
-shift lock under the gear shift has gotten very loud whenever you press or release brake pedal.

All of these issues seem to be the same wether the car is running or not. There are other issues with the car, but these seem to be the most obviously related to electrical problems. I'd like to come up with some remedy for these and see where to go from that point. I've done some research and have some ideas to what the problem may be, but I'd like some input if you have any to throw my way.

My thoughts:
-bad ground connection. If you know of ground wire locations to check, please let me know.
-bad voltage regulator/alternator. I don't know if this only regulates battery charge, or overall power to everything. I have tested the voltage across battery posts while running. 13.4v at idle. 13.15v with fan on full blast.
-bad battery. I haven't had it tested, I also don't have trouble with it trying to crank. Seems ok.

Any help would be much appreciated.

-Slumbo

Post by **Ozark Lee** » 10 Sep 2014, 07:14

Welcome to MVS,

They symptoms you describe are typical of a bad B+ cable. That is the secondary cable that branches off of the main battery terminal and then goes to the front, kidney shaped, fuse box. In many cases you can actually see that the connection in the fuse box has overheated but a voltage drop test between the battery terminal and the secondary B+ terminal will tell the story. The voltage drop shouldn't be more than a couple of tenths of a volt. Another place to check is the stud from the positive battery terminal where the B+ cable bolts onto the main terminal. That can get corroded as well.

...Lee

Post by **BEJinFbk** » 10 Sep 2014, 08:41

I'm hearing at least three separate issues:
Low voltage - start with cables and connections. Search " Voltage Drop".

A broken servo in the ECC. Usually a DIY repair.

A bad microswitch in the shifter console.The shift lock solenoid
should only operate when the car is in park. If yours clicks every
time you hit the pedal, the microswitch that detects when the car
is in park has a problem. Usually they fail open. Sounds like yours
failed closed or is out of adjustment.

Slumbo · Post by **Slumbo** » 10 Sep 2014, 09:21

Thanks for the info. Good stuff. I will look into it after work and keep this thread updated.

-Aaron

Slumbo · Post by **Slumbo** » 11 Sep 2014, 02:53

I am getting a .5v drop from the battery to the fuse panel. I didn't have time to really open it up to see what the B+ cable looks like, but from what I've read it seems safe to say it needs to be replaced. My ground connections behind the driver's headlight and beside the fuse panel were fairly corroded. I removed and cleaned those. The voltage across the battery terminals increased by .2v while the car is running, but it didn't seem to help with the dim lights, etc... (I was waiting until this morning to post this, when I had an opportunity to drive in the dark.)

As for the shift-lock; it seems to be working properly, I just don't remember it being so loud! Surely I would've noticed it before. I don't know. Maybe not.

I suppose I'll be ordering a new B+ cable now...

Thanks!
Aaron

Post by **timmybdaddyof3** » 11 Sep 2014, 03:15

swap the B+ and see what happens....you may have many issues, but they could all be related; and your finding of a .5v drop is without a doubt the place to start.

Once you get the new cable in test it again and then start chasing grounds....the last thing you want to do when chasing system wide electrical issues is introduce system wide variables. The cable may solve your issues and the grounds may just need to be addressed as preventative maintenance, if you start pulling them apart before you get the cable in the question will forever loom of is there a ground problem, or is it a problem you caused.

let us know what you find

Slumbo · Post by **Slumbo** » 11 Sep 2014, 11:55

I ordered the cable this morning. Hopefully I'll have an update by early next week.

-Aaron

Post by **rmmagow** » 11 Sep 2014, 13:51

This is pretty good for the B cable info:
https://www.matthewsvolvosite.com/forums ... hp?t=35208

Slumbo · Post by **Slumbo** » 16 Sep 2014, 06:57

So I installed the new cable yesterday and took some readings with the voltmeter. The voltage drop has gone from .5v to 30mv. So that seems good. But the symptoms seem mostly unchanged. There may be a bit of improvement, but hardly noticeable.

Here's a thread I had come across that pointed me toward the voltage regulator, which may or may not be my issue.

http://m.volvoforums.com/forum/showthre ... &styleid=5

I bought a regulator for like $35, but man it looks like a real pain to change out. What readings should I get to try to narrow it down? Or just take it to autozone and have them run an alternator test?

Aaron

Post by **Ozark Lee** » 16 Sep 2014, 07:21

The Autozone (et al.) chain stores can effectively test the alternator under load while it is still bolted up in the car and it is a free service. I would definitely go that route first.

...Lee