Hey guys,
I have a Problem with my '87 IROC-Z28 (L98).
The voltage-meter only Shows ~10V although the Battery hast 12.6V. I don't think the voltage-meter is defect because when the engine is running it Show 13.xV.I'd assume there is some Kind of ground-problem. To Check this I Changed the Battery cables with Ines from innovativewiring. Mine were...shortly before burning the Car down.
the cables are the beefy ones you See on the 2nd Pictures. These are Not the correct ones for my model year but they Work. Maybe I have to Re Run some of the small cables but Generally IT IS fine.
This did Not fix the Voltage shown in the Dashboard with the Battery connected.
I am Not a pro when IT comes to Car elextronics.

Amy suggestions / Tips how I could tackle this Problem?

As the next step I'll Bridge the gnd from the Battery to the Point on the Firewall to See If there is a Connection issue. My GND from the Battery ist connected to the alternator beackert, might that cause a Problem?







Furthermore: does anyone know the Name of the 3 Pin connector in the Battery cable?


Thanks for your Help,
Greets from GermanyMax

 

The one thing I'm 101% certain of here;

The big battery ground wire MUST connect to the engine block itself, not to the alternator bracket, not to the cylinder head, the block is the only acceptable place for it.

Resolve the improperly connected wire, then check all the other ground wires (the small one from the battery's - terminal to the car's body and the ones on the back of the cylinder head).....

 

I've Just attached the large ground cable to the bottom of the engine block.
this did Not Change anything. The Dashboard still Shows ~10V.
I also tried "bridging" between multiple Points (Frame, Firewall, engine block) and the negativ Battery pole.
this did Not Help either.

May there be some fault in the alternator or charger? I find IT quite strange that the Voltage with the Battery is shwon to ne ~10V and with the engine running it's the correct 13V.


Thanks for Further Input
Max

 

Max, I think you may be paying WAY too much attention to that "gauge" !!!!!!

Now, I know that because your in Germany your used to German cars with their very accurate dashboard gauges, but here your talking about a mid 80s American car, and unfortunately "accuracy" wasn't much of a consideration with these things to start with. In fact, our gauges are so infamously inaccurate that one of the most third gen informed guys on this board calls them a "trim package" and won't even refer to them as "gauges" due to their lack of accuracy!

With that said, the actual usual charging voltage is usually closer to around a wee bit over 14 volts, and on our cars it's best measured with a precision voltmeter of the type electronic technicians usually use, I generally favor my trusty Simpson 260 for when the actual voltage is required to be reliably measured. Does the car start ok? Are there any other electrical malfunctions that cause you to suspect a low voltage condition? If not, if it's just the gauge reading that's got you worried, I'd say your very likely fine but if your really concerned any good VOM will tell you all you need to know

 

If you want to know what voltage the gauge is really seeing then you could remove the dash to measure voltage at the electrical connector behind the dash.

The volt gauge in the dash only knows what voltage it sees across its own body. Any voltage losses on the supply side before the gauge, or the ground side after the gauge will cause the gauge to read a lower voltage.

If you find that the voltage is okay then you can "calibrate" the volt gauge by removing the needle and rotating it a little clockwise so the number reads okay.

 

Thanks for your help guys.
Actually the voltage shown by the gauge is only something I noted. The "main problem" is: the car wont start when it is warm.
If the car is cold it will just start fine, but if it gets warm it wont anymore. That's why I thought there might be a voltage/ground problem. I assume the voltage going to the starter motor is "just enough" when everything is cold. Due to the increased resistance of the warmed up car it wont start when everything is "Hot".
But actually I have not tried that. I just refered to the gauge after changing the cabeling. I will drive the car to work tomorrow and see, if it starts "hot". If not, it has the whole day to "cool down".

I'll report back...maybe my problem is already fixed...and I just did not notice that duet to lack of proper testing.
I will also check the charging voltage with my multimeter tomorrow.

I have a spare starter motor and alternator laying around - if the problem is not fixed I might change them.
Additionally: Where is the starter motor relays located?

Greets,
Max

 

When you say it won't start when it's hot, does the starter crank the engine too slowly to start, or does it not crank at all? As to your starter relay question (leading me to wonder if it doesn't crank at all being the reason your asking about a starter relay?), the short answer is that there isn't one, as the enclosed 1987 wiring diagram shows. If you look at the bottom right hand side of the diagram you'll see that the power to engage the starter's solenoid comes from the battery through a fusible link, then on to a red wire feeding the ignition switch , switched by the start position of the ignition switch and sent to either the clutch start switch or the gear selector switch (manual shift VS automatic) on the yellow wire, and then from whichever of the two possible safety switches it has straight to the starter's solenoid on the purple wire. If you car was new enough to have VATS, there would be a VATS relay in the starter solenoid's power path but VATS didn't come to our third gen cars till 1989, so you will find no factory* relay in your starter's solenoid circuit.

* I say "factory" because some aftermarket alarm systems do have a relay that gets wired into the starter's solenoid circuit, but in pure stock "as built" factory configuration there will be no relay .......

 

Thanks for the hints,

the alternator is delivering about 13.6V to 13.8V (measured with a volt-meter). I assume that is not really enough. I'll try re-tightening the alternator belt - maybe thats just the culprit. If not, I might replace it. Concerning the new battery: it is fully charged, I charged it over a day before installing it and it reads 12.6V. I assume the car does not have a VATS - it's mostly stock.
I drove the car to work today (20km / 12.4mls). It started fine this morning. After arriving at work I tried to start it "warm", I tried to crank, but did not really. I'll try if it will start again when the engine is cold this evening. If I try long enough the engine / starter will not crank at all.

Any further suggestions?

Thanks
Max

 

So,

after work I wanted to drive home but the car wouldn't start. At first it tried to crank but it did not start. After that it didn't even try to crank. There only was a "clack" sound from the engine compartment but nothing would turn. Even when connecting the battery of one of our company cars it did not work. Just the clack-sound....
I assume my starter is locked / dead now?
Any suggestions on how to start the car one more time to drive it home?

Greets
Max

 

13.8 is too low, mid 14, like right around 14.7, is what you should be seeing. Were the jumper cables you tried to use nice heavy duty ones with big fat wire or were they so called "booster cables" that will carry enough current to charge a battery over time (like 1/2 hour or so) but not enough to jump start a car right then & there? I'm not even close to being ready to condemn your starter yet, to me it sounds like your starter isn't getting enough power to operate, which of course if this is true wouldn't be the starter's fault. So the battery rests at around 12 volts, all well and good. What will be most telling here is what is the battery voltage as the key is turned to start? And again the battery voltage measured on both the big and small terminals on the starter solenoid when the key is turned to the start position?

 

Bad starter motor getting heat soaked?

 

It's fine, the alternator is working. The system voltage would instantly drop to less than battery open circuit voltage (something less than 12.6V) if alternator was not able to keep up.

 

Thanks for your help guys.
I'll check the alternator again if I get the car running. If I understand everything correct it should supply 14V or above. Maybe my belt was just slipping on the alternator, I re-tightened it but can't check right now because it wont start.

I used "heavy duty" cables. But we have different ones at work, maybe I'll try those today.
The voltages I should measure are:
1. Battery Voltage when I "start" the car.
2. Voltage on small and large terminal of starter solenoid with ignition on but not cranking, I assume.

I assume the voltage on the small & large terminal of the solenoid should be equal to the battery voltage?

I will check these - probably tommorrow and report back. Thanks for the help guys.

 

I had thought this also, but then elnitschko said it wouldn't start after sitting parked at work all day, so I don't think heat soak is at fault here.

One bad diode in the alternator could have the unit putting out less that it should be, leaving the alternator not totally dead, but not able to keep up with both charging the battery and powering the car's other electrical demands.

 

Again, if the alternator can't meet electrical loads then system voltage will immediately drop below battery open circuit voltage because the battery is supplementing power (discharging). No need to think the alternator is bad when it isn't behaving like that. 13.8V is spot on and well within tolerance.

 

Yeah, on second thought I'll agree here.

It'll be interesting to see if it turns out to be starter or perhaps bad connection related.

 

Hey guys,

I worked on the car yesterday and the culprit was the starter motor itself. The solenoid worked fine but the starter would not turn. The new starter worfks perfectly fine. I now have some ratteling sound but I assume it's just a piece of the exhaust system not tightened properly. The alternator with the newly tightened belt now delivers 14.7V. The engine now starts immediatly.

I've two questions: what thread and length are the starter motor bolts? The original ones were to long for the "new" starter. We have spaced them out so they fit for now (added a large nut as a spacer) but I want to mount it properly.
Additionally there was a metal bracket on the back of the alternator (towards the car front) which connected the alternator to the engine block. The now alterantor did not have a screw to attach said bracket to.

Thanks for your help guys,
Max

 

If the "rattle" noise happens only when starter motor is cranking, then it might be that the starter gear backlash is too tight and you need a shim under the starter mounting pad so to position the pinion gear a little further away from engine. Usually (in America) shims come in the box with the starter motor.

 

That shim was actually inlcuded with my alternator. I was asking myself what the prupose was.
The ratteling sound continued while driving - not only while starting. In the beginning it was only noticeable when I accelerated slightly. After I arrived home (16km / 10mls) the sound was continously. I just hope the tolerances are not so tight so the starter does not dis-engage. Any way ot check this?

Greets
Max

 

If the starter didn't disengage from engine then it would have been destroyed within the first couple minutes of engine running. Like utterly destroyed, would never work again.

 

A friend of mine just told me that if the starter motor bolts are to long the starter motor might be wrong...it might be one for a 4th gen with LT1.
I heard the starter motor botls are "centering bolts" and if they don't engage properly it might damage the engine block...I think I'll just order an ACDelco alternator and see if it's dimensions fit the ones of my starter motor...

In the following picture you the see the "bracket" on the backside of the starter motor - the picture is from an 84' corvette I think. Sghould this piece be present in an 87' L98?

Edit: I found the solution in my service manual: this bracket seems to be stock...but only on my '87 Camaro, not my friends '88 Firebired I compared it with.





Greets
Max

 

Okay, this is my very first posting. My '87 iroc will start when it's cold. It tends to run hot. When it gets hot and I park it for around 15 minutes and try to start it, it will either just click, or make no sound at all. It will need to cool down, or be jumped with heavy duty cables. I've replaced starter, alternator, and battery. I am thinking it's the fusible links at starter? Maybe someone can confirm or debunk this. Also, how bad would it be if I eliminated fusible links?

 

Eliminating the fusible links is every bit as bad as the ol "I'll just put a penny in the fusebox" (go ask an old person what this means), or playing Football without a jockstrap ....................

You WILL end up taking a flaming kick in the nuts !

Since millions, maybe even billions of cars function perfectly well with their fusible links intact, it's a pretty good bet that those AREN'T the root of your problem, a fusible link is either 100% good or 100% bad(burnt open) . Since your electricity passes through the fusible links just fine when the engine is cold, that means that they aren't the problem when the engine is hot (Fusible links don't magically "heal" themselves with differences in temperature, they are a piece of wire after all) . When an electrical overload burns a fusible link open it's open, period, and whatever was being powered by it gets no electricity whatsoever, whether it's hot or cold. Your problem most certainly is elsewhere, and here's how you should proceed ;

Take a proper voltage measurement between the large connection on the starter and the metal frame of the starter motor itself when it's hot and won't start, and the voltage reading you obtain will be the first step in your troubleshooting.......