checkmate1996

*** Solution ***
5/14 - I have GM delco conversion setup. Long story short, the pigtail plug that goes into the alternator went bad. It lost continuity between the red wire and the plug. Oh brother! Nontheless, after cleaning all the contacts on the back of the pod, etc, I now chargding at 14.2v! Yeah!
*** Solution ***

Ok, just recently my alternator quit charging ... again. I fixed it last time because it was just a loose connector in the back of the pod. Not so lucky this time though...so here's what I have done and know ... of course any suggestions appreciated.

One other wierd zinger. If the car sits for a while, when I start the engine, the alternator WORKS for MAYBE a minute or less; give or take...then quits. If I restart immediately, nothing.

- Confirmed the following with all pod connections in, ignition turn to 'ON' and exciter wire removed from alternator
- B+ voltage is registering 12+ volts
- Red wire going into pigtail is registering 12+ volts
- No voltage at (green) exciter wire end which goes into alternator
- No voltage O8 in the fuse panel
- No voltage at Z1/Z6 in the fuse panel
- No Voltage at H7 or H8 in the fuse panel
- No voltage at 1R / 2R pod connections under the dash

However, I did confirm:
- ~25 ohm resistance / connectivity between 1R/2R at the dash and at H7/H8. (That should put aside any thoughts about breaks in circuit board behind the dash)
- However, I'm thinking that the resistance feels low but I don't know what it SHOULD be.

What do you guys think? Other than it's been running perfect and I'm dying over here with all this nice weather!!!

fbarnhill

Brad, wouldn't the AC/Delco single wire swap solve this issue? I thought you were going to look into that a while back. How the heck are you these days anyway. The car looks great... I bought an 88s4, so old blue will be for sale some time soon.... Enjoying them both for the moment though.

checkmate1996

Frank! Great to hear from you too!

I did do the AC DELCO Upgrade/Swap along time ago and it's been working great. Unfortunately, this is something above and beyond that.

Maleficio

Are you saying you're not getting exciter voltage to the alt, but you've verified the circuit is intact?

WallyP

1R receives power from Bus 15 thru H7.

Check for 12vdc on H7 with the ignition switch ON.

If there is power, the problem is likely to be in the black wire from H7 to 1R or its connections.

If there is no power on H7, check for power on the red/black wire in H6. If there is power here, the problem is likely to be the connection from the 15 bus to H7 behind the Centrl Electric Panel.

checkmate1996

Thanks wally, I am going to check h6 because h7 and h8 are definately not getting power...

checkmate1996

Update:


Interestingly, I let it sit overnight and I took some measurement prior to cranking the engine.
The pigtail end read .02V. So did H8. H6 and H7 read 12v.

I then plugged the pigtail back in to the alternator and while the car was running took some new measurements:

H6, H7 - 12v
H8 - 0.00v

So I'm starting to get a sneaky suspision there is a resistor/pod issue....

Does anyone recall what the ohms of the resistor is suppose to be?

Landseer

Resistor itself should be 68 ohm.

This should help you diagnose.

BTW, how is terminal 1 of your 14 pin connector?

checkmate1996

Landseer...I just went back to MY old thread on this same topic and saw you posted this there.

Ok - I'm so confused ...

h6,h7 consistently post 12v. H8 nothing.
I then measured continuity & resistance between h7 & h8 - 150 ohms as expected

Then I went over and bent my back under the dash (uggh) and measured term 1 and term 2.

Voltage on t1 was .03v
Voltage on t2 was .03v
resistance between the t1 & t2 was ONLY 18 ohms....

I did verify continuity between h7 and t1. CHECK.

something is just not making sense here ...and I don't know what it is!!

tailpipe

just hotwire it from ignition power at the fuse panel to the exiter circuit wire going to the alt I chased my intermitant open circuit for yrs trying to find it in my 78. The only downside to hotwiring like this is when the key is on the power is always flowing so will kill the battery if you leave the key on

checkmate1996

Well I could simply hotwire from h6 which is a switchable powersource so you don't have to drain your battery and is a short run. However, it WAS just working perfectly and then it failed on me briefly a few weeks back but then 'it' kicked back on and at that time I thought it was just an anomaly. Then it happend a week on the way to work. Then finally it just quit all together this past week. So it was a rather quick, but gradual death.

My guess it's something simple, but the behavior of this issue is really strange.

I recently verified that I had continuty between:

T1r -> h7
T2r -> h7

but nothing between h7 & h8. Which according the diagram one would think there should be continuity.

Landseer

I'm learning with you on this and want to demistify the murkiness on this circuit once and for all. Don't let me hijack in the process, please.

I might have expected about 48 ohms between H7 and H8 if unplugged from the CE panel and measured within the plug with . (this would represent the combo of resistor and light in the circuit).

I'd expect H7 to have 12v with key on, due to it tying to the 15 bus. H8, also. I think it all grounds all the way back to the alternator, untill the alternator gets energized, then the alternator returns 12v up the line to match what its getting from the 15 bus and cancel the light in the process. So, with exciter disconnected at alternator, and key in on position, shouldn't you see 12V at the end of the exciter wire?

Also, note that the 14 pin connector is involved in this circuit (T1). Also, O8 on the CE. And the factory alarm module. O8 feeds H8. But runs through the alarm to do it, else the appropriate Zplug jumper if alarm is not fitted. That's what I see on the diagrams, at least, so you might check / confirm.

So the problem might be in the dash or might be in the other part of the circuit as eluded to.

Here are a few diagram snippets that might help. The alarm I could not find in the wiring diagrams and had to hunt in ancilliary places.

Landseer

So, the way I see it, the flow path is as follows:

Alternator little wire...
into the 14pin connector at T1, and back out...
then into O8 into the CE panel
where O8 = Z1 (due to spaghetti connected behind panel)
Then out CE panel on Z1 into the alarm, then through the alarm and back into CE on Z6 (if alarm is fitted / or directly through jumper wire at panel if alarm is deleted)
Z6 happens to equal H8 due to wiring behind panel.
Wire H8 leaves the CE and goes to the pod where you have been working....

H8 goes into the pod on one of the terminal traces you mentioned, where it connects to one side of the bulb and , in parallel, also to one side of the resistor, then....combines back together to represent another wire trace....

(In the pod, the light represents 170 ohms, the resistor 68 ohms. In parallel, there should be 48 ohms measured across them, based on the math above in that training document.)

It exits the pod on the other terminal you reference, and heads back to the panel where it comes into the panel as H7.

Behind the panel, I guess H7 connects to the 15 bus / key circuit, where the power comes from when you turn the key and get the little red alternator light.

Hopefully Wally will read this and either bless off on it (or tell me to erase it all).


The way I think it works: 12V is passed from H7 through the pod and all the way to the alternator where the excitor wire is grounded at rest.... but where it generates a counter-current of 12V to cancel the light when spinning.


OK. You asked for help and I'm trying. If this is f'd, we erase it or fix it. Just trying to help.

checkmate1996

landseer, I appreciate all of your help...trust me!

I think you are on the right track, but I'm pretty sure the flow is from the POD TO the Alternator based on how I'm reading the wiring diagrams..


(h6 provide bus power)--> T1 - T2 -> h7 -> h8 -> Z1/Z6 bridge ( I have no alarm - so I have the bridge) -> o8 -> T14 #1 connector spot -> then to alternator.

I'm pretty frustrated for now...so I am taking a break from it ...

Landseer

H6 looks to be fused 15bus power to illuminate the instruments and power them and their lights, including voltmeter,but I don't think its is powering the alt light / exciter, which is a special circuit from rest of instruments also. Perhaps not part of the equation, depending on whether the car just isn't registering the charge vs not charging.

H7 is fed behind the CE panel from a direct unfused connection to the same bus 15, which is switched on when key is in on position. Same bus, different path I think.


Remember that these delco alternators are a fast solution with a price point thats favorable, initially, but my experience with delco base generic rebuilds on other cars is they fail far earlier. They can fail intermitently too. So your circuit may not even be the problem.

Maybe do a bunch of continuity tests on the wire, check for broken 14 pin connector T1 wire solder (intermittent possible here too) and disconnect the exciter at the alt and see if there is about 10-12V on the exciter wire as it approaches the alternator (with key on).