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Replaced LQ1 alternator, now something very strange happens...


crazyd

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i timed it, and, it is almost exactly two minutes. i unplugged the backup switch on the tranny, but it wasn't lighting my backup lights either. i can literally shut the car off while going down the road, turn it back on, and buy myself another two minutes.

 

Okay folks, enough about the alternator ducting, I've got a serious problem I really need help with. I'm still no closer to a solution at this point. I've tried disconnecting the EGR, IAC, TPS & O2 to see if they have anything to do with it, and the alternator is still shutting down when I touch the throttle even slightly, once warmed up. This seems to be directly related to the ECM going into closed loop mode, but I can't think of any other reason for that to have an impact on the alternator. :think:

The ECM should be in closed-loop at idle when warmed up. Some older vehicles will drop out of closed-loop at idle due to lack of sufficient heat on the O2 sensor--but not a W-body (that I'm aware of.)

 

Therefore, open loop vs. closed loop should have NO effect on your alternator.

 

If the belt isn't slipping, my first guess would be DEFECTIVE ALTERNATOR and/or defective regulator inside the alternator. Since this has happened to you on two different alternators, you've checked the tensioner, and there's no evidence of belt slippage, this theory also seems flawed.

 

I'm kinda confused about this being a time vs. throttle position problem. At one point you said it happens repeatedly at two minutes. Another time you're saying it happens whenever you push the throttle, or when you drop the trans into gear. I'd appreciate some confirmation about when the alternator quits.

 

Tell me this: My 92 Lumina keeps the dash lights on for a short time after startup. Might be two minutes, maybe less. I've never paid that much attention to it. Seems to be on a timer circuit for some but not all of the interior lights. Does your vehicle do this? Does the alternator die at the same time that the interior/dash lights go out automatically?

 

Does the dashboard indicator for the alternator/generator work properly? My '92 Lumina has a voltmeter, but I'm thinking--and I should know this because I've owned the thing since November '92; and I drive it almost every day now, but have utterly failed to notice--isn't there ALSO an indicator light for the charging system? Does it come on during bulb-test? Does it come on when the alternator quits working at the two-minute mark, or when you put it in gear, or touch the throttle, or bark at the moon, or whatever it is that you do to cause the alternator to shit the bed?

Edited by Schurkey
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Put an ammeter on that alternator output wire, tell me how many amps the alternator is throwing before the "three-minute time limit".

 

First Guess: alternator is over-charging, getting hot, and some protection circuitry is shutting it down. This ties in with the "three minute operation". I am not aware of protection circuitry in older alternators/regulators--but I don't know squat about the 130D. I know that some alternators have the regulator built into the ECU rather than stand-alone, or built into the alternator. I wonder if the ECU has the ability to shut the alternator off if it senses massive over-charging.

 

Second Guess: Failing belt tensioner. Any sign of belt wear? Any other accessories not working properly--P/S or A/C, for example? I say this based on you having problems when the RPM goes up.

 

Third Guess: Assuming that the ECU isn't playing games, and the belt tension is acceptable, I'd be probing the pins inside the alternator connector. What is happening at those pins at the three-minute mark? If the field coil is getting power...the alternator should be outputting. How does the field coil lose power? Since this problem has happened with two alternators, it does not seem to be an alternator problem--therefore must be somewhere else in the vehicle including the wire harness. If you put the vehicle in reverse, is the rocking of the engine/transaxle enough to pull on the wire harness enough to stress the harness?

Whatever happened with these suggestions? Did you ever perform those tests?

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okay, since this is a GTP it has a voltmeter gage with no warning light. The only thing that shuts down the alt is when i touch the trottle after a few minutes from cycling the ignition, otherwise it will sit at idle or coast, and charge normally. and it is not just the gage, because the lights dim when it cuts out. it is nearly impossible to try to probe the pins because the car must be running and revving to reproduce the problem.

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did you try switching some wires around on your alt plug? my earlier suggestion of the self exciting internal circuit mod IS real and a good alternator shop can order one and install it for you and it would get you by. but when I first did swap over to the cs130d it was a matter of seeing which wire configuration on the plug would get the job done. the shop did it for me though as I watched.

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Just did some searching and couldn't find a self-exciter kit for a CS130D, though there is a full replacement available for $209. That's an interesting idea, I might just do that and save myself more agony over this problem.

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Just had a really interesting and informative chat with the people at alternatorparts.com. This appears to be going back to my original problem with adapting the CS130D alternator wiring in the first place. Here's the text description of what we were discussing.

 

http://alternatorparts.com/cs130_sbpage2.htm

 

The L wire should have provided a switched 12V source to fire it, but in 2007 when I checked it I was getting less than 0.5V. So back then they had clued me in on this S terminal and I rigged the bypass wire - and it worked. S is supposed to be Sense voltage, I have no idea why it actually worked. But now it seems that it was down more to a quirk of the particular regulator I had in that particular alternator, rather than a generic solution to this problem, because there still needs to be a good 12V source to either the L or F/I terminals to excite the alternator properly, and this could be why it's shutting off.

 

Fig3.jpg

 

So, my plan is to dispense with the S terminal bypass wire altogether, and find a good switched 12V source and run that to the L terminal with a resistor. My hope is that the F/I wire will have good 12V, so I may just need to reverse them.

Edited by crazyd
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Well, an afternoon's worth of work later and it is nice to know that the S wire was never even necessary, but the problem still remains. I got about 6V on the wire that was on the F terminal and 0V on the L terminal, so I reversed them and it worked, but only until it warmed up and I gave it some throttle, exactly as before. This points back to swapping in a self-exciting alternator, if I can find one with the correct mount points.

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S terminal basically allows for for an external voltage reference for the alt, rather than an internal one.

L terminal needs to have a ~35-500 ohm load on it between +12V and the terminal, the check guages or volt lamp is usually what is used.

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S terminal basically allows for for an external voltage reference for the alt, rather than an internal one.

 

Can you elaborate on what this means? I'm not clear on why the alternator would need an external voltage reference.

 

L terminal needs to have a ~35-500 ohm load on it between +12V and the terminal, the check guages or volt lamp is usually what is used.

 

Where else would be a good place to get a switched 12V source near the alternator then?

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S terminal can be useful when you have really lossy cables... basically, instead of sampling the voltage that the alternator is producing, you can sample voltage elsewhere, like at the battery terminals.... you could also use it to target different charging voltages, higher and lower.... i wouldn't recommend doing that without some serious forethought though.

 

switched 12V near the alternator? ...... the closest location i can think of off-hand would be either IGN fuse in the right-side electrical center.

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  • 2 weeks later...

So I did some research and found a self-exciting regulator at alternatorparts.com. I went down the part number listing on that page and the question I have is, are those alternators that HAVE that regulator already, or are they ones that are COMPATIBLE with it? I pulled up a vehicle cross-ref listing and found these 94-97 2.2 S10/Sonomas use that part #. So I checked my local self-serve yards and found a '97 S10 with a 4-cyl. Went over to take a look at it and lo & behold, it had nothing plugged into the regulator. I pulled the regulator and thought I'd give it a try. Pulled my alt back out, desoldered the stator wire and installed it.

 

Same problem.

 

I'm not sure what this means, but I'm just going to order the self-exciting reg from alternatorparts and hope like hell it works, I've had it with this problem!

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  • 3 weeks later...

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