A Hot Time in the Ol' Fiero Tonight (Page 2/4)
olejoedad JAN 30, 03:08 PM
I have seen C500 from several different years featuring a light green wire for the Block Ground circuit ....C500 A2.

As the picture is oriented the alphanumeric code is this

1. 2. 3. 4. 5
E
D
C
B
A
olejoedad JAN 30, 03:10 PM
Just saw your last post.

DOH! It happens, dont feel bad, it could have been worse!
theogre JAN 30, 03:54 PM

quote
Originally posted by Notorio:

Ogre, I didn't see your reply until after I tried something. I did misread the figure Olejoedad pointed out and immediately found a huge mistake on my part: the direct short of power to ground. Definitely a Doh! moment.

CLICK FOR FULL SIZE


Above you can see I've got the green & black wire stake on connected to the positive terminal of the starter (!!!) So I removed that and attached it to the grounding lug towards the right side of the picture. This brought the resistance of the green-melted wire to < 1 ohm.

I decided to attempt a crank over with the coil plug pulled. When I climbed into the cabin I noticed the AJAR, the OIL, and the TEMP warning lights already on (at about half strength.) Turning the key to ON (but not CRANK) those lights brightened up to normal and several other lights came on. A brief crank shows the Starter and Tach are working. One additional issue: the fuel pump did not go on. I rechecked that and sure enough it was silent.

Status: Perhaps I've blown the Fuel Pump fuse but I can't account for the lights that are ON when the key is OFF.


black and tan are all grounds. Not sure what what has green ground. Not digging thru entire 88 FSM to find more.
tan is O2 sensor "ground" tied to ECM. Is a "Fake" ground like an ECM "Ground" to HEI. See my Cave, Ground "Myth" notes

May have wreck ECM or other things using those ground lugs. They are supposed to use stud top trans bell bolt or equiv near the starter.
ECM and FP relay should have turn on the FP then shut off if you don't start the engine.
connect light/meter betwwen aldl G to frame then turn key on
Notorio JAN 30, 04:59 PM
OK, I'm going back into the connector to trace the other wire on the 'fat' pin before looking for more melted light green wire. Here is an updated status (i.e. I had the lights incorrect above and corrected them there and now here):


quote
I decided to attempt a crank over with the coil plug pulled. When I climbed into the cabin I noticed the AJAR, and the BRAKES, VOLTS, and the OIL warning lights already on (at about half strength.) Turning the key to ON (but not CRANK) those lights brightened up to normal and several other lights came on. A brief crank shows the Starter and Tach are working. One additional issue: the fuel pump did not go on. I rechecked that and sure enough it was silent.

Status: Perhaps I've blown the Fuel Pump fuse but I can't account for the lights that are ON when the key is OFF.

Status: With the key OFF the back up lights do not light.
Notorio JAN 30, 05:41 PM
The cap is now off the C500 connector which has allowed me to confirm the pin assignment:

E2 - purple wire (with battery disconnected, reads <1 ohm to ground)
A2 - melted, light green wire (with battery disconnected, reads <1 ohm to ground)



As per above the Purple wire goes to the Starter Solenoid. That should NOT be at ground, right? So that would mean the Light Green and the Purple wire have melted together 'somewhere' in the harness.

Before going through all the pain of removing the harness from the car, if I disconnect the Purple wire from the Starter Solenoid and the wire is Good, it would have infinite resistance to ground, yes? If it is still well grounded then that would Prove the wire is damaged, yes?
Notorio JAN 30, 07:14 PM

quote
Before going through all the pain of removing the harness from the car, if I disconnect the Purple wire from the Starter Solenoid and the wire is Good, it would have infinite resistance to ground, yes? If it is still well grounded then that would Prove the wire is damaged, yes?



Answer is ... purple is still grounded. Interestingly, the purple wire has a companion wire going into the same stake on which is maybe a light orange-brownish color with a fusible link within inches of the starter solenoid connection. No other wires have continuity at the C500 connector to the melted green or purple wire. Perhaps this means the fusible link is blown? Of course none of this sheds any light on why the Warning Lights are ON even when the key is OFF.

I'm ready to concede ... looks like this weekend I'll be pulling the wiring harness and taking it apart.
theogre JAN 30, 07:47 PM

quote
Originally posted by Notorio:

The cap is now off the C500 connector which has allowed me to confirm the pin assignment:

E2 - purple wire (with battery disconnected, reads <1 ohm to ground)
A2 - melted, light green wire (with battery disconnected, reads <1 ohm to ground)

CLICK FOR FULL SIZE

As per above the Purple wire goes to the Starter Solenoid. That should NOT be at ground, right? So that would mean the Light Green and the Purple wire have melted together 'somewhere' in the harness.

Before going through all the pain of removing the harness from the car, if I disconnect the Purple wire from the Starter Solenoid and the wire is Good, it would have infinite resistance to ground, yes? If it is still well grounded then that would Prove the wire is damaged, yes?

C500 A2 is a Ground connected to other grounds including at lest 2 in Cabin.
FSM says Dk Grn but may had color change from 30+ years of oil etc on it plus heat now... Other end is likely part of lugs on starter above...
CLICK FOR FULL SIZE


Cook ground(s) may or not short out unless burn other like purple one might have but any cooked wires will have problem carrying power loads and water will eat them fast.
Very likely other wires are burn too.
Should pull the console to look at G202 for a start. Screw to the tunnel near ECM.
Pull C500 body side for same reason. I think 2 small screws plus plastic "duct" and whatever go w/ that to protecting the wires.

Starter and solenoid is a ground path so have to disco the purple wire before testing.
Might pass but insulation still burn by it or A2 and have problem later. Purple wire is bigger and less heat in it vs A2 when burning.
Or A2 burn into other small wires and have same problem or is shorted now.
IOW burn A2 wire can burn any to all wires in the engine harness near it. Not just C500 wires but ECM wires go directly thru rear firewall. Plus same issue for body side C500 wires etc.

May cooked I-switch and clutch switch. If not bad right now can bite you later.

Note that XΩ to ground or pretty much anything w/ any normal meter means very little here. Wires > 18awg is too large to really test w/ any Ω meter using 9v or smaller battery.
Can use Voltage Drop testing w/ car running but is dangerous w/ possible burn wires.
Are tools to test iffy wires but very few has access to them or know how to use them. These "meters" called collectively Meggers can generate Hundreds to Thousands of Volt to look for bad insulation etc. (Megger is a brand name but others are called that name regardless name on label. Even many Commercial Electricians don't have them because real ones that meet safety standards etc cost a lot w/ "Cheap" ones > $500)

[This message has been edited by theogre (edited 01-30-2020).]

theogre JAN 30, 08:07 PM
Above shows the tan wire too. Look toward the right of the box.
Both go to same stud/bolt...

[This message has been edited by theogre (edited 01-30-2020).]

ltlfrari JAN 31, 08:24 AM

quote
Originally posted by cvxjet:


(I just checked and my backup lights come on with the shifter in reverse- but the key OFF! Is that right? (I would think it would be "Key power")



According to an 87 wiring diagram I have (I assume all years are the same), the reversing light circuit is hot in run, bulb test, or start only.

------------------
Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

theogre JAN 31, 09:19 AM

quote
Originally posted by ltlfrari:
According to an 87 wiring diagram I have (I assume all years are the same), the reversing light circuit is hot in run, bulb test, or start only.

True
But
You didn't read this thread? Or are you one of using a phone/tablet or other small screen/window to read and can't/won't to really look at images?
Because I already posted 88 BU light wiring in http://www.fiero.nl/forum/F.../HTML/143417.html#p8
Image: BUlight88.png Dimensions: 1456 x 1068 px, 38.5 x 28.3 cm, 15.17 x 11.13 inches
And Why I use Img Thumb for them so can read the text w/o big images all of the time. Nice that new img button takes PNG but often need to save big images and use whatever or Print to view because of new img auto size.

Besides that the rest of the thread found the problem and I posted more data from 88 FSM...