Ignition switch losing voltage?

[Craig 94 TA GT]

I'm having a problem where the car is losing voltage as it warms up. First thing in the morning, the voltage shows well over 13, maybe 13.5-14 on the dash. On the freeway, it stays up there, hanging around 13. Then, as soon as I encounter traffic, it drops a bit. Then, once the fans need to be kicked on, the voltage drops into the yellow. 550 idle in an auto makes it drop even further. Putting it into neutral, 650 rpm idle, helps a bit. I've been having this issue for years and have replaced many things electrical (ICM, coil, alternator) but it had 0 affect. A multimeter shows the battery around 12-12.5 off. So my question is, sine the dash reading is after the ignition switch, could the switch itself be where I'm losing some voltage? I attached a pic of a typical reading sitting in traffic, but it can get a lot worse than this. Thanks in advance.

[Jeff_in_Atl]

I doubt it. Can you take the alternator off and take it to get it checked? Most parts stores will do it for free.

['STANGETR]

I usually have that problem in the summer, especially when I'm running my AC. One time I came to a stop to turn and my turn signal started slowing and stopped because there wasn't enough juice to run it. Someone made mention on here that that is more a problem with the automatics and try putting in a higher amp alternator.

[Joe 1320]

Mine had that same problem since the day I bought it new from the dealership. I put an overdrive pulley on the alternator and there was no change. I eventually put a higher capacity alternator in the car and the current is higher and more stable.

[Craig 94 TA GT]

Thanks for the tips, guys. I currently have a 140 amp PowerMaster that had been load tested by a shop, but I didn't see that much improvement over the stock alternator. Maybe about a half volt at most. I could have sworn, when I first got this car (and up until a few years ago) the voltage was always 13+ even in hot traffic, but I could be wrong. I didn't have a fan switch before, which seems to drop the voltage more than anything. This is one reason why I opted for PCMforless to keep stock fan settings - cause it seems to suck so much voltage, when it's already low to begin with. Maybe I'll give a new alternator a try, or have it tested again.

[Joe 1320]

It may test fair when cool, but I'll bet the voltage drops when it builds up some heat.

[Rob B (shoebox)]

Yes, the dash reads the voltage after it has gone through the ignition switch. The power connection there typically gets overheated and the tension of the connection can get weak. When it is warm out, I often see a whole volt or more less on the gauge than what is at the battery.

[Craig 94 TA GT]

I did some testing, and when I saw the voltage in the yellow in the dash, I checked the battery. The battery itself read 13.67 volts. So I replaced the ignition switch and gained 1 volt at the dash under typical conditions. I kept the blue harness because it looked fine.

It still drops to the yellow in heavy traffic with lights and fans, but shoots up to ~12.5-13 when the RPMs go from 550 to 700. It didn't shoot up that quick before. But at least it's better. Maybe I'll try the fuel pump wiring next, since the switch powers that.

[Craig 94 TA GT]

After a long time with the motor build-up, I'm still getting low voltage. I haven't had a chance to run all tests yet, but from what I'm seeing:
- Idle is now up to 900 RPM for the new cam, yet voltage at dash is well into the yellow, about 11 volts. It fluctuates a bit, maybe by about .5 volts
- Battery voltage with a multimeter reads 12.9 to 13.05 volts and seems to flucuate between those (but could be the multimeter doing that?)
- Idle seems to be getting a bit rough. Not sure if this has anything to do with voltage

Battery is a brand new Delco. Maybe it's time for a new alternator? When the motor put in, I'd assume the grounds were cleaned or ok. But I guess I can't rule those out either.

[Rob B (shoebox)]

If you want to easily compare non-switched voltage to switched, you can use your meter in the underhood fuse box and touch the little test points on top of the fuses. Very easy to compare that way.

[Craig 94 TA GT]

Thanks Rob, I'll check that tonight after I get home from work. I'm definitely curious to see what comes up.

Another observation on the way to work is that the dash gauge shows yellow all the time now (except for the first few minutes at cold startup). It seems to dip 0.25 worse, at times, when driving on the freeway with higher revs. Idle seems to have the most volts (especially when the brake lights aren't on). It's only a difference of 0.25 to 0.50 volts, but I would have thought the alternator turning faster would mean more voltage. I guess not in this case.

[Craig 94 TA GT]

Driving home to work today was bad - volts were almost down to ~10.75 on the dash. Lights seemed to be a bit dim too. The alt output was well under 12.

However, the problem is fixed! It was the alternator. Luckily, I had a spare. Put it on, and idle now shows 14.2 volts. The dash showed well over 13 with lights and fans on. So I think this issue was unrelated to the original post. Originally, it showed low due to the ignition switch. But I already changed the switch, so this time it was the alternator.

I had the A/C compressor freeze on me recently. Snapped the belt and made a mess of rubber chunks and particles all over. I wonder if it had anything to do with the alternator going bad. Probably not, but just a thought.

[BrdWAtti2d]

Good to hear you got it solved. Now on to that ABS light, lol. Mine comes on too, drives me loco.

[Joe 1320]

However, the problem is fixed! It was the alternator. .

Hate to say it, but........


told ya!

[Craig 94 TA GT]

lol, I know Joe - sometimes I always think too hard to realize the obvious! I'm really glad it was that, and not something that takes a while to find, like a loose ground, or the new ignition switch.

BrdWAtti2d, I would love to get the ABS fixed, but I lost it when I put the 9" in there...but I did have problems with that light before that - ever since I did the first spark plug change a while back. Couldn't figure it out for the life in me, so just ditched the ABS with the new rear