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On acquisition, the alternator isn't working. It has a remanned Bosch that Bob installed, but it stopped working. I've been working from this list of instructions from Stan from another post:
Originally Posted by Mrmerlin
here are a few tests you can do .
Turn on the key so all of the warning lights come on , do you see a red light on the charge gauge?
If not the bulb is blown replace it..
If the light does come on then
start the car and without revving the engine check the voltage at the hot post it should be above 13.5, .
If not the rev the engine and see if the charging system is then giving this reading.
if it does then the is probably a break in the charge wire that goes to the alternator it runs through the 14 pin connector.
remove the blue wire from the back of the alternator and separate the 14 pin connector see if you have continuity from the engine side of the wire to the blue wire on the back of the alternator.
If not then the wire is damaged and it will usually be broken about 4 inches up inside the red sheathing from the alternator this is from hanging the alternator on its wire harness, find the break and rejoin the wire
Here are my results:
I have a red charge light.
With the engine idling, voltage at the hot post shows battery voltage.
When revving the engine, voltage at the hot post shows battery voltage.
I have continuity from pin 1 to the exciter wire where it goes into the back of the alternator.
With the ignition on, I have .4v at pin 1 of the 14 pin connector and at the exciter wire.
Assuming that I'm correct that pin 1 is the upper left pin in this picture:
According to this post, .4v at pin 1 is not enough voltage:
Originally Posted by Speedtoys
Well long story short, if there isn't 6-7v at the exciter wire at the alternator, good battery, key on, car off...there's something that needs fixed I believe.
I've poked around and I didn't find anything helpful for low voltage at pin 1.
Can someone validate my troubleshooting so far and suggest next steps?
OK to be clear the lower half of that connector is the car side that goes to the CE panel. The upper half goes to the engine.
SO with the cover off the rear of the alternator remove the blue wire from the alternator post and check continuity from the wire end to the 14 pin top connector.
You have checked the battery terminals for tight?
you have cleaned the 3 red wires at the hot post?
you have cleaned the grounds above the CE panel.
You have inspected/cleaned the ground straps at the battery ground and the engine to chassis ?
Even with no exciter voltage, or even no wire even attached for the exciter, a blip or two of the throttle, to 2k rpm, will self-excite a good alternator.
Does your charge light stay on after the engine is running?
Time to pull the alternator
Thats a beautiful car The paint looks perfect, I cant wait to see it in person
Thanks, Stan. Really, it's 10 foot paint, but I'm planning on getting the rubbies removed, so maybe a complete respray instead of just matching on the doors.
If I can't figure out this problem, you might be seeing it sooner rather than later.
Awesome Shawn. And great choice - my first shark a long time ago was an 84 S ruby red. I had the gray/tan and brown interior. It was an auto. Fantastic car. I have a soft spot for the 84's too!
I installed a rebuilt Bosch alternator last summer that worked for one day. It seems to be a common occurence. I sent it back and put in an old original Paris Rhone unit off ebay that works but needs to be revved above 2k RPM to kick in and the bearings are noisy.
Moving on to Stan's instructions. Let's start with a pic of the alternator with the rear cover off. Everything seems clean and tight. I assume the exciter wire is in the right place, because that might be an easy fix.
Originally Posted by Mrmerlin
SO with the cover off the rear of the alternator remove the blue wire from the alternator post and check continuity from the wire end to the 14 pin top connector.
I checked resistance from Pin 1 to the terminal end of the wire.
You have checked the battery terminals for tight?
Yes, the terminals were nice and tight. I disconnected them to drop the alternator.
you have cleaned the 3 red wires at the hot post?
Everything at the post looks tight and clean.
you have cleaned the grounds above the CE panel.
You have inspected/cleaned the ground straps at the battery ground and the engine to chassis ?
I was interrupted by work, but I'll get at these tomorrow.
01-07-2021, 08:14 PM
Adventures with my new 1984 S.
