New 928 owner. Alternator problem.

[tedward515]

So a few weeks ago I finally got a 928. It’s a stock 81 US spec 5 speed, metallic black with black leather. I’ve always wanted one as long as I can remember. I love the way it drives and the way it looks. It needs its share of work and I’ve been doing a few things like new tires, plugs and wires etc… while driving and enjoying.

The other day I noticed that my volt meter was reading nothing. I didn’t think a lot of it and thought maybe the gauge was bad because, the car is 27 years old and everything else (lights, radio windows etc….) was working fine. I parked the car, went inside and came back out a few minutes later and it wouldn’t start. I jumped it and headed out hoping that all was well (rather optimistically). It started fine, but progressively lost power. So I figured my alternator wasn’t charging and that I was running the engine on the battery. Luckily, it died across the street from an auto parts store. So I took the battery in and had them test it. They said that it was bad and I bought a new battery. The car started up fine and I had them do there test on the alternator. They said that it was fine and the battery was the problem all along. I drove it home and everything seemed to be fine but the voltmeter still was reading nothing. Less than a mile from home the voltmeter went to 12 and the low gas light that was on got about twice as bright. I also noticed that the turn signal light was much brighter and the radio got louder and brighter also. I’m skeptical about the auto parts store testing of the alternator. I’m still wondering whether it is charging properly or maybe I have a bad ground? Any thoughts will be greatly appreciated.

Thanks in advance
Eddie

[Danglerb]

Cleaning all the grounds is a good start, also the dash gauge is less trustworthy than a campaign speech, measure at the battery and the jump post with a real meter.

Common problem on the 928 is the old wiring and switches that can cause a drain on the battery even with the key off. This kills a new battery, then the low battery kills the alternator, etc. Testing the alternator is pretty brainless, they spin it with a motor and measure the output, so if it tests good, I suspect its still good.

Another problem can be the exciter wire to the alernator, but start with cleaning grounds and proper measurement of the voltage.

Nice Car, welcome to the group. These old beasts do shine up pretty don't they?

[surfdog4]

wow your '81 is a lot prettier than mine! What's that red thing in the garage????

Does the alternator light come on when you start the car or when the volts read 0? The charging circuit for the alternator runs through that light bulb..so if it is burned out the alternator never charges.

Also like danglerb said the instrument cluster is frought with contact issues..could be faulty contacts, grounds, etc etc..especially if you are seeing problems with other gauges.

On my '81, the oil pressure gauge was always pegged, the speedometer would not go above 30mph, the voltmeter jumped up and down constantly, and the temp gauge was dead...(other than that the cluster was fine )

Once i redid the contacts, everything worked (and i figured out i had a bad alternator)

[devilinblack]

Yeah, don't get me started on alternators.

I'm converting to an AC Delco one that is much cheaper and higher amps, but I've uncovered an electrical gremlin with my charging light. So far I'm on my 3rd Delco rebuild in as many days.

Another option, after you clean the grounds would be to remove the alternator (it comes out pretty easily) and take it to an alternator repair shop and have them test it. I don't have a whole lot of faith in any of the chain parts stores these days since it's a rarity that you find anyone who knows more about cars than how to start and stop them and maybe strap some neon tubes underneath.

[BLK87S4]

Also consider pulling your relays and checking them for corrosion. If there is any, clean them. Corroded relays caused me a wrold of trouble including sluggish starting as they were an overall drain on the system.

[tedward515]

Thanks everyone for the suggestions. I will be working on it this weekend, and hopefully I will have some good results to report back. Oh, and the red thing is a 71T that I'm slowly taking apart to restore.

[Landseer]

You should cycle through the grounds and clean them.

In particular, get the two that are on bolts above the CE panel (passenger floorboard), firewall. You may need to remove the wooden covers from that area.

Also, get the one that is in the trunk area, drivers side slightly, that the negative battery cable is attached to.

Also, take apart the 14 pin connector in the engine compartment against passenger fender and clean out corrosion.

The charge exciter wire in particular, along with other harness wires, fail. Sometimes they break inside the insulation or fail intermittently. Its the little wire on your alternator. You can check continuity by putting a meter between its end and terminal #1 inside the 14 pin connector. It is also the same as terminal 8 on the back of CE panel plug O.

That said, the alterators seem to fail often. My strong recomendation, at least to get started, is go to the auto parts store and get a 105A alternator listed for the 1988 V6 Camaro and an off the shelf pigtail for it. Connect your alternator wires to the + terminal bolt. Except the little wire, the exciter wire, it should be attached only to terminal L on the pigtail Connect none of the other three pigtail wires, they need to be removed. This should get you going.
I wouldn't trade-in the core, it might still be good, you could have it checked, it can also be rebuilt as parts are available to the DIY'r. The vent cover will not fit, you would need to run without or fab one. Note that the fenderwell on the drivers side has the vent hose, which contains an important outside air sensor used by the Bosch fuel injection system as data, so don't axe it.

The conversion is economical. Again, your alternator might be fine, then what I've suggested for the conversion is not so sensible, you can figure out the order in which you test / try stuff, but this information should help you.

[N2O-SHARK]

If your exciter wire is bad, reving above 2000 rpms should self excite the alternator. If you let the car warm up and lights are still dim, but when you blip the gas once they brighten up and stay bright.. it's your exciter wire. Trouble with self exciting is the alternator can loose it later if you stay below 1500 rpms a lot.

Stock alternators are too small for the shark if you even add an aftermarket stereo.. Lots of folks switch to the Delco, or have the Paris-Rhome or Boschs rebuilt with more amperage. I had mine rebuilt with 160a core for about $250. I can run everything now and lights are always bright.

[tedward515]

Ok, so it’s taken a bit longer than I hoped but I think I solved the problem. While cleaning the fuse/relay panel I saw a couple of jumpers and in my infinite wisdom I pulled them. So I put the connector that I assumed went there and tried to start the car a little later. Instead the alarm went off. So I assumed it must have been the connector that I had just reconnected. I pulled it and the alarm shut off. I started the car and everything seemed fine. Until what I described above. A couple of days ago it dawned on me that it would have something to do with the connector. After plugging it back in and learning how the alarm works (ie don’t lock the car) everything is back to normal. So now the question is. I don’t know which terminals to connect the jumpers to so I can lock the car yet still have a functioning electrical system.

The other thing I’m wondering is if there is supposed to be a piece of plastic or something other than the round spring loaded piecein the lower receiver of the tailgate latch.

I have some pics but I have to resize them a little later.

Thanks

Eddie

[rhjames]

if you have an owners manual or the factory workshop manuals, a picture of relay/jumper placement on the central fuse panel will be in either one of these manuals. (someone here could post a picture---)

the hatch receiver is just as you describe--nothing more.

(and your window trim is supposed to be powdercoated black---you can paint with a flat black paint to get the same affect, if you don't want to go to the expense of powdercoating them)








--Russ

[Danglerb]

Pictures would help, like of where you are moving these jumpers around. Kinda hard to guess.

If I can find it, I'll post a hatch receiver picture below. Note the rectangular rubber sleeve, which wears out and may be missing.

[785sp]

Hey Eddie, let me save you some trouble.

I have basically your car and have had the exact same issues. I went through four "rebuilt" alternators in 15K miles. For the last one, I went to my oil-change guy (for the wife's car) and said "Where would you send out an alternator to be rebuilt if you absolutely had to make sure it was an A+ job?" He directed me to a local shop that's mostly industry walk-ins. I went there, chatted with the guys, and when they realized what kind of stock, alternator I had (which I had purchased at full "rebuilt" price from a reputable 928 supplier), they started to hedge and said they'd have to "consult" with their parts supplier. Eventually, they replied that they could re-build it properly, but they needed a couple of special parts, at a little more cost. Now, I know what you're thinking, that I was just being hosed an extra 50 bucks, but guess what: it's worked perfectly ever since. The bottom line, I suspect, is that the stock alternators have some parts that are not always replaced in the run-of-the-mill rebuild, and those are the parts that often fail. So, either you hunt down a rebuilt shop on your own and make them do it right, or you find a pricey "totally new" alternator (if such a thing exists--I've been told that the "new" alternators are probably rebuilds anyway), or you convert to an ACDelco or something else that's more standard.

Also, I still haven't solved the exciter-wire problem, but letting the older 928 models sit at idle for hours is a terrible idea anyway (unless you like loud explosions), so that's probably a minor issue all things considered.

[SolReaver]

Not all alt rebuilds are the same. Most are good with the bearings and brushes. The big difference is in the Diode block. Most Alts have diodes that rectify the current generated. A simple bench test is good most of the time but can miss an intermittent problem or irregular current.. A good alternator rebuild shop will test the unit and give you a readout of amperage vs. rpm. 50 bucks is a little pricey for the diode block on its own so I am thinking that they had to take the unit apart, install a better diode pack and then test. Definitely worth $50.00 considering all the time and aggravation it will save you.

After cleaning as many connections as you can think of. Make sure that the alt has bee given a professional going over and be sure that you have a readout of rpm vs. amps.

[Landseer]

Guys, do whatever you want with the rebuild. The Bosch and Paris Rhone alternator rebuild parts are available to you online and you can DIY.

But to get started and eliminate that variable, get the Delco. Lighter, more amperage. Works 84 and back. Can work 85 / forward if you substitute the older steering pump bracket and alternator bracket. Then, after you sort-out the other electrical crap you can retro the original.

[m21sniper]

I had all kinds of problems with alternators in my 928 until i switched to a Bosch. The Paris Rhome units are total ****. I switched to a Bosch and have never had a problem with charging since.

[Landseer]

Agreed. I've had two fail, both on 84's.

The last one had diode connections taken-out by nut shells that some enterprising rodent packed into the cover. Was a partial and intermittent failure at first. Then showed steady low voltage. Then, within 15 miles progessed to a total failure. Could see the broken parts on disassembly. Posted pics here somewhere.

[surfdog4]

Not knowing better at the time, i jumped on a rebuilt Paris-Rhone i found on ebay..it fixed my immediate problems, but i can tell it's really weak. If i had to do it over again, i would buy the Delco unit.

[m21sniper]

Personally, i'd opt for the Bosch. Delco rebuilds can be pretty crappy.