Hello all,
1st owner of 2002 Camaro Z28 with ~103k miles.
Haven't visited this forum in years.
Been having intermittent non-start issues which have now gotten worse.
Of course when I need it to give me problems (at mechanic) it works just fine.
Decided I need to finally trouble shoot this as walking to work is not going to fly.

Before going through the details here is what I observe.

If car is functioning normal. I insert key, dash lights come on and go off as expected. Car starts.

​​​​​​​When car does not start. Turn key to On and there is a "click" under the dash. I can predict with 100% certainty that if I hear this noise the car will not even try to turn over when I turn the ignition switch to Run. This leads me to think it is not a starter solenoid issue 9common discussion point tin many threads) as at this point that should not be involved. Would make me think it is something between ignition switch and the starter relay that is causing the problems. Security light goes out as normal leading me to think not a VATS issue. My best "guess". is I have a faulty intermittent clutch switch or ignition switch, however, ..................

Found this thread which seemed to provide the best information (from WhiteBird00) on how to trouble shoot this:
https://ls1tech.com/forums/wiring-st...h-battery.html
I will copy the info below in my post in the hopes that someone can help me further.

I can not thank WhiteBird00 enough for the information in the thread and any others wiling to help.
I also found a helpful wiring diagram but can't recall from which site.

From WhiteBird00, Post#12 in thread above: (and my comments inserted)“Let's start with some diagnostics at the starter relay. There are four wires at the relay:

Dark Green - battery positive voltage from the STRTR 15A mini fuse in Junction Block #2 via the clutch switch (or PNP switch in an automatic)
Red - battery power from the IGN 50A MaxiFuse in Junction Block #2
Yellow/Black - starter relay coil ground controlled by the BCM (VATS)
Purple - starter relay output to the starter solenoid"

Im not sure how to loosen the box to see the colors for the wires and I don't want to break it but was able to find the "Hot at all times" (red wire) is in the upper right slot for the four pin relay, if you are facing in from the drivers side. This told me that my relay was technically upside down as the lettering was right side up from this position. My understanding is that one can switch 87 and 30 and hence 85 and 86 it will still function (and it came that way from the factory) but it was puzzling at first that 87 seemed to be hot at all times. This is correct yes? does the same apply for the ignition IGN relay and all other four pin relays?

So in my discussion this is the ideal relay pin configuration (and supposed colored wires underneath) when viewed from the driver side - meaning the lettering on the relay would appear upside down:
86 (YEL/BLK) 30 (RED)
​​​​​​​87 (PPL) 85 (DRK GRN)
​​​​​​​These are where the relay pins would go and hence where I probed for the following.

"To save time, the first thing to check is the STRTR 15A mini fuse. Never rely on a visual inspection (especially of a 13+ year old fuse) - it could be blown but still look fine. Use a tester or replace with a known good fuse. Do the same with the IGN MaxiFuse although if it was blown, basically nothing related to the ignition would work so it's probably fine."

Both fuses appear fine and had continuity when checked with ohm meter. I cleaned the 50A fuse with a scotch pad although it looked fine.

"Now if that didn't solve the problem, we start checking with a test light or multimeter. In this case a test light will be simpler since we don't have any computerized or solid state components to worry about and we only need to test for the presence of power or ground. Test for constant power on the red wire. If no power, look for a break in the wire someplace between the IGN MaxiFuse and the relay."
Found constant power with ohmmeter in the upper right hand slot = which determined was where pin 30 should go.

Now you will need a helper. Have them in the car ready to try the starter when you are under the hood testing. Check that the dark green wire gets power when they try to crank the engine. If not, either your clutch switch or the wiring between the fuse and the switch or between the switch and the relay is bad.

Dark green (85) shows voltage with ohmmeter when the clutch pedal is pushed in and the ignition switch is set to start/run so at least at this point in time that all seems fine.

At the clutch switch, check for input power on the purple/white wire then check for output power on the green wire when the clutch pedal is depressed. That will determine if it's the switch or which side of the wiring.

Did not do this as the above worked. Could be intermittent clutch switch or ignition switch so maybe I need to revisit this? My mechanic at one point checked the clutch safety switch and said it seemed fine - I think he pulled it and checked it with a meter but will need to verify. It was over a year ago....

"Back to the helper. Check for ground on the yellow/black wire (86) at the starter relay when the helper tries to crank the engine. If no ground, either you have a break in the wire from the relay to the BCM or your VATS is preventing the ground (although the SECURITY light in the instrument cluster should be illuminated or flashing if VATS is the problem)." Multimeter showed no voltage before cranking with no change while cranking. Is this correct way to check for ground?

"Those steps should help you nail down where the problem is located. Don't assume anything - always test to confirm.”

After this I put back in the relay and the car started so I am not sure where to turn to next. It certainly is not fixed. Im thinking I have some corrosion somewhere, maybe an intermittent clutch safety switch ? Any recommendation on what to check next?

Question 1: Is there a sticky on this issue?
(I can come back later to post visuals/pics if that is helpful for others but for now I'll proceed with text)

​​​​​​​Question 2: How do I loosen the engine fuse box to get access to the wires underneath it?

Question 3: If I jump 30/87 locations this should cause the starter to turn over - even with the ignition in the off position, correct?

Question 4: If I jump 30/87 with ignition in ON position then the car should actually start (as the fuel pump turns on just fine) and then drive as per normal. I could carry around a jumper for those times when it won't start. I know I would need to remove jumper quickly after car starts to prevent the starter from continuing to engage and engage the clutch its so a bit of a dance.....In reality I won't be driving it until I am convinced it is actually fixed....

Question 5: Does it matter if the relay is turned 180 degrees, i.e. 87 and 30 are switched etc.

Question 6: How do I diagnose this further - other than just start replacing parts?

Seems to be intermittent - clutch switch (cheap) or something with ignition switch (cost?) or some weird VATS issue (although the light goes of per normal). Not sure where to go next and don't want to take it to my mechanic until I can't fix it or I can't determine what else to do.......next thought was replace or short the clutch safety switch..........

​​​​​​​Thank you in advance!

 

Let me try to answer your questions in order (bear with me - it's a long post and I may miss something)...

With standard (called Bosch style) automotive relays, the 85 and 86 terminals are for the relay coil which triggers and releases the internal switch in the relay. They are generally reversible although some come with internal diodes to help prevent decay and 86 should be used for power in those (doesn't apply to this case). Similarly, 30 and 87 are interchangeable as they are the power source and switched output of the relay. 30 is normally used for power, especially in a 5-pin relay with an 87A terminal but there is no reason they can't be reversed in most cases. It's easy to determine pins 87 and 87A because they are oriented perpendicular to the other pins.


Bosch style relay pins
(87A may not be present)

Yes, this applies to the other 4-pin relays which allows you to swap a suspected faulty (or intermittent) relay for another of the same size. In this case, Fan Relay #2 in the other junction box would be a good choice because you would still have fans although you would lose high speed if the relay really is faulty.

Yes, according to my schematic, you have the pin assignments correct.

It is possible but unlikely to have an intermittent clutch switch. That would generally only happen if there was excessive grime in the switch and your reported physical inspection of the switch probably eliminates that.

Now, checking for ground is the reverse of checking for power. This is where a good old fashioned test light is really simple but a meter will still provide good results. You need to touch the red probe to a power source (the big terminal at the end of the junction box is a convenient option) then touch the black probe to where you want to test for ground - in this case the yellow/black terminal. If you see full battery voltage on your meter then you know you have a good ground.

I am not aware of a sticky on this subject.

I couldn't find any mention of a procedure for removing the junction boxes in the factory service manual. I assume there's a bolt and possibly one or more plastic clips. Unfortunately, I haven't had my T/A for over 10 years so I can't go out and look. Perhaps another member can offer some advice.

Yes, jumping the 30 and 87 pins (red and purple wires) will turn over the starter even without the ignition switch... you're essentially bypassing everything to route battery power to the starter.

I would not rotate the relay. Actually, I would have thought that it would not be possible because of the aforementioned arrangement of the pins with 30 and 87 oriented at right angles to each other. But even so, swapping with a fan relay would be a better option.

Intermittent electrical problems can be the most difficult to diagnose. The best option is to do these same tests when it actually fails in hopes that the failure will last long enough to test for the cause. I'm afraid I don't have much else to offer you at this point.

 

Did you try replacing the ignition relay? That's a common issue with 4th gens.

 

Thank you for all the information, especially checking for ground as I clearly was not doing that right!!
Starter/IGN Relay in this car all the pins are parallel so 180 degree rotation switches 30 and 87 fine.
87A is flush with surface and perpendicular. I'll also note that the orientation/placement in the electrical diagram of the pins does not match up with their reality in the real world - nor the schematic on the side of the relay - but maybe thats normal for electrical circuit drawings?

Going to prepare a roadside starter kit so I can bypass the issue when needed without a helper.
Since my investigation car has been ok - go figure!

 

I did not as everything related to that seem to function fine. I'l look back at the diagram and see if I am missing something there,
I do have an extra relay I can put in if needed though.
Thank you!