Overcharging

[minigts]

I'm at a loss and not sure where to check next. I've read a couple of threads and there seem to be possibilities with the LM when there is a socketed board and also loose negative battery terminals. While it could be the first, I don't think it's the latter because I've checked everything and all the wires seem to be grounded well.

With as much detail as I can provide, here it goes.

• Car has a socketed LM and a for the most part basic cal with +20s and a 3 bar MAP sensor (87 electronics LM in an 86 electronics car)
• Alternator is the Nipendenso unit. I've tried multiple ones and all yield the same result. Ok voltage initially, but eventually it goes up and will stay pretty high.
• Swapped two different power modules, both yielding the same result
• Voltage measured tonight was around 16.5v
• Voltage seems to vary based on the RPM, for the most part. Usually once it starts to rise, it will stay high until the car is turned off.
• It MAY seem to be more of an issue when it's cold, but hard to say for sure.
• High gauge ground wire bolted to one of the studs (non-field related) on the alternator that is also bolted to the motor mount bolt.
• Voltage dropped to just below the battery mark on the stock gauge at one time, then came back up to the first high warning indicator. This has happened multiple times. One time it did that for about 25 minutes as I drove home, although the car didn't die. Almost like the alternator went out.
• No spare socketed LM to swap out.
• Seems to have been going on for a little while, not sure how long though. The cutting out issue just started recently though.
• MY COMPUTER DOES NOT POST CODES, so please do not ask what codes I have received. While there could easily be a link between the issues, I doubt it since the codes have not worked since I got the car 2 years ago and this problem has been something recent of an issue.

I can check the cal to see if there is something set in there that may be causing an issue, but I don't know what to look for. Any advice would be appreciated.

[Tbird232ci]

Have you thought about trying an external regulator? It would remove all LM/PM control of the charge voltage.

Personally, I think it is in the LM. I had some overcharge issues, and it would cut out and give me a Power Loss light. I forgot what the code was, but it was an overcharge code. I was driving around with my blower motor on to keep the voltage down. My issue turned out to be a lose ground terminal (LOL). Bottom line of this story is that if your LM is functioning properly, it should be throwing a code for overcharging.

Have you checked the pin leading into the LM? Pin 22 on the blue connector is your voltage sense pin.

[Khajjathefang]

Your voltage regulator is hosed, an external conversion is easy and will fix it no problem.



I used an autozone replacement for a 80's fullsize pickup with a 318. Works great and the three post terminals were easy to fab connectors for

[shackwrrr]

I'll have to pull a wiring diagram but one of the disable links provides a battery sense feed to the power module. If this has too much resistance the PM will see a lower voltage and increase the alternator output to compensate.

[cordes]

I thought you had tried a different LM at one point?

[minigts]

Have you thought about trying an external regulator? It would remove all LM/PM control of the charge voltage.

Personally, I think it is in the LM. I had some overcharge issues, and it would cut out and give me a Power Loss light. I forgot what the code was, but it was an overcharge code. I was driving around with my blower motor on to keep the voltage down. My issue turned out to be a lose ground terminal (LOL). Bottom line of this story is that if your LM is functioning properly, it should be throwing a code for overcharging.

Have you checked the pin leading into the LM? Pin 22 on the blue connector is your voltage sense pin.

I hadn't thought about the LM, but I just swapped another one I had with a stock cal and 2 bar MAP and got the same issue. I'm going to check all the wires in my book against what the red and blue connectors should have for the 87 TII electronics and make sure I don't have one backwards or out of place. There are a couple that move in the conversion and for a bit I was swapping from stock 86 TII to 87 TII, so maybe I missed a wire or something.

Your voltage regulator is hosed, an external conversion is easy and will fix it no problem.

I used an autozone replacement for a 80's fullsize pickup with a 318. Works great and the three post terminals were easy to fab connectors for

I will do this if I have no other alternative. Unfortunately I'm a neat freak and would have to wire it in such a way that it was unnoticeable. :\ But I did see your write up before and thought about doing that whenever mine went out.

I'll have to pull a wiring diagram but one of the disable links provides a battery sense feed to the power module. If this has too much resistance the PM will see a lower voltage and increase the alternator output to compensate.

I have the 85 books, but if you have anything for the 87 TII, I would appreciate it. I have everything detailed from Russ Kinzie's site (I think it's his site), but the actual pages would be good to have.

I thought you had tried a different LM at one point?

I don't think I tried one for this issue, I don't think. It's really become a problem recently and I'm worried it is doing damage to the pieces in the harness that can get ruined, like the injectors or the LM or the Ostrich I have hooked up. Going to go through the diagrams and confirm everything is as should be.

[cordes]

Well, I can't believe it but Moates doesn't list the specifications for the Ostrich on their site. I would think that it should be able to handle 18Vs, but I was hoping to give you a little piece of mind.

Also, I'll try and dig up the 87' TII charging diagrams in my FSMs after waffles.

[minigts]

Well, I can't believe it but Moates doesn't list the specifications for the Ostrich on their site. I would think that it should be able to handle 18Vs, but I was hoping to give you a little piece of mind.

Also, I'll try and dig up the 87' TII charging diagrams in my FSMs after waffles.

Well I think most of the things in the car can handle it, I'm assuming they have internal regulators of sorts to manage that. More concerned about the injectors really I guess. Obviously the system is reading 16+ volts at the battery, so that will translate everywhere else until the problem is resolved. Hard to imagine that two power modules, two alternators and two LMs would yield the same results. I must have a wire not in right place.

[minigts]

Alright, I checked the voltage at the LM and everything seemed ok. Of the wires that get power, none seemed terribly out of range and all the wires are in their correct spot. The LM was reading about 14.2V on some of the wires that are fed it from the PM, but nothing went over 14V when I rev'ed the car. Other voltages were in the neighborhood of where they should be, one being the voltage sense that ran anywhere from 9-12V if I remember correctly. Basically, nothing seemed to be getting the 16+ volts I was reading at the battery. But that bugs me because why is the battery getting so much voltage? I don't think the PM would regulate that. But does it or does anyone know how that works? At this point I don't have an issue putting in a voltage regulator if that is logically the problem. Hard to think that two PMs could have bad regulators, but I guess it can happen.

Any thoughts?

[cordes]

Was the battery voltage high when you took those measurements? It seems very odd to me that the battery would be reading high while no other place would be. The alt is putting out 16V when the battery reads high correct?

[86Shelby]

According to your searching, the PM feeds the LM so could there be resistance/poor connection in one of the wires that feeds the PM which could cause lower voltage for the rest of the PM/LM system? Have you checked resistance on the grounds for both the PM and LM? For the circuits you checked going to the LM is the voltage the same at the other end of the wire?

Have you checked the voltage elsewhere in the car to see if everything else is getting the 16V? something like the radio, taillight or blower motor circuits? They could be checked pretty easily at the fuse box. I'm just throwing out ideas to see if anything sticks.

[minigts]

Was the battery voltage high when you took those measurements? It seems very odd to me that the battery would be reading high while no other place would be. The alt is putting out 16V when the battery reads high correct?

I did not, but my biggest concern was the system sending too much voltage to the LM or elsewhere. I was in the car doing the readings, revving the motor as I could.

According to your searching, the PM feeds the LM so could there be resistance/poor connection in one of the wires that feeds the PM which could cause lower voltage for the rest of the PM/LM system? Have you checked resistance on the grounds for both the PM and LM? For the circuits you checked going to the LM is the voltage the same at the other end of the wire?

Have you checked the voltage elsewhere in the car to see if everything else is getting the 16V? something like the radio, taillight or blower motor circuits? They could be checked pretty easily at the fuse box. I'm just throwing out ideas to see if anything sticks.

I haven't, but I will. And it's hard to really check without driving the car. While revving the motor seems to yield results, there will be times when I will start the car and drive it for a bit before I see any change. Usually it will happen within a decent period of time, but it's not RIGHT when the car starts. But I will check the voltage at the battery and the LM at the same time to see if I get consistent readings.

[cordes]

87' G body TII scans as requested.

I have a couple of concerns regarding the testing and I know they aren't easily solved by one guy with a meter trying to track down this phantom problem.

1. I worry that you're unable to detect a voltage with no load on it.

2. Since it takes a while for this to happen could there be just enough heat buildup in the length of wire to cause a substantial enough problem to occur?

I know you could solve the first one by putting a very small load on the wire with an LED capable of handling the voltage you're feeding through it. If you had a few resistors around you could use any 5mm LED to produce a voltage drop without killing the LED. Of course if you have 5 or so LEDs lying around which you don't mind frying a burnt out LED would mean that there probably isn't sufficient enough voltage drop to be the cause of your problem.

I really don't envy you on this one Jon. It reminds me of my crazy boost problem I had in the black Omni. The only problem is that with your car the wiring is tip top by any standard making this a real doozy to actually track down.

ETA: You should see if the computer will put out the signal from the check engine light wire at the LM. Then you'll know once and for all if it's the actual LM/code or if it's the wiring to the light/cluster/bulb. Of course if you've already done that ignore what I just wrote entirely!

[minigts]

87' G body TII scans as requested.

I have a couple of concerns regarding the testing and I know they aren't easily solved by one guy with a meter trying to track down this phantom problem.

1. I worry that you're unable to detect a voltage with no load on it.

2. Since it takes a while for this to happen could there be just enough heat buildup in the length of wire to cause a substantial enough problem to occur?

I know you could solve the first one by putting a very small load on the wire with an LED capable of handling the voltage you're feeding through it. If you had a few resistors around you could use any 5mm LED to produce a voltage drop without killing the LED. Of course if you have 5 or so LEDs lying around which you don't mind frying a burnt out LED would mean that there probably isn't sufficient enough voltage drop to be the cause of your problem.

I really don't envy you on this one Jon. It reminds me of my crazy boost problem I had in the black Omni. The only problem is that with your car the wiring is tip top by any standard making this a real doozy to actually track down.

ETA: You should see if the computer will put out the signal from the check engine light wire at the LM. Then you'll know once and for all if it's the actual LM/code or if it's the wiring to the light/cluster/bulb. Of course if you've already done that ignore what I just wrote entirely!

Not going to repost the pics. Thanks for the diagrams too!! I needed a copy and this will suffice until I get the books, one day.

I'm sorta in a rush as I just found out that my house is to be shown in a couple hours. First, the alternator died. Well let me clarify, I think this is the second one that has died. I mentioned before that the power level dropped on the way home one time. That time I actually pulled the alternator and replaced the innards with another one I had lying around. I'm assuming that it fried the internals and I'm also assuming this happened to this one as well. I have one good one left and have put this on the CSX and will be driving that until I get this squared away.

I didn't get a chance to test the voltage elsewhere and at the battery due to the alternator dying. I plan to order some rebuild kits to fix the two that have died, although I may just go buy a new one and see if the older ones are just dead. I can't imagine that being the case since I pulled the one good working one from the CSX and then it died in my GLHS. There is definitely something going on and maybe it is the voltage regulator in the PM that is allowing the alternator to push too much maybe? Again, not sure how electricity would work in that instance, but if the alternator can just put out whatever it gives, I'm sure it would wear it's own parts and eventually possibly kill itself.

I will see if I can rig something up to do some testing when driving, but it will have to be when I rebuild one of the alternators and get it working again. Also, I haven't tested the theory you proposed about checking current at the LM when pulling codes, but I can tell you that the fuel pump primes EVERY time you turn the key, regardless of the number of turns. So I'm not 100% sure it would yield any positive results if I checked the PW light wire directly at the LM or not since the fuel pump isn't supposed to prime after you turn the ignition 3 times.

Gotta run, but I'll post back up when I get the replacement or replacement parts.

[cordes]

When it rains it pours. The alt overcharging can certainly kill them quickly. Honestly, running at 16V like you are is a testament to the durability of the components.

Best of luck with the showing!

[Khajjathefang]

I also had two PMs acting up/go bad. Would short the radio out if I didnt run highbeams everywhere. Car was so much happier with the external I'd just convert any new project td I got.

[5DIGITS]

The PM regulator is the typical cause poor voltage regulation with the 10 and 14way 'pinch-fingers' terminals and LM terminals next in line.
In the case of a PM failure, the voltage regulator connection (solder joints) are the usually the culprit.
Narrowing it down even further, when the heat sink on the regulator becomes covered with road dirt and/or corroded, it loses thermal rejection capability.
The worst case situation is caused when the PM regulator has dirt covered/corroded heat sinks and no means of airflow (air-box breather tube or other) is being provided.
(see regulator reference pic)

If you open the PM and use oil or WD-40 on the BiWax rubberized coating, it will allow you to see the regulator pins and the solder joints.
Browned, dried, or cracked coating on the backside of the PM, in the area of the regulator OR connector areas, are tell-tale signs of poor connection and the resulting excessive heat.
Dig out the rubberized coating, re-solder the regulator and connector pins as needed, and correct the 'pinch-finger' terminals with a small paper clip or stick pin.
(Note: The round housing of the 10/14way terminals is not the contact area, as seen in the reference pic below, therefore squeezing the round portion of the terminal is an incorrect approach)
Re-seal any repaired solder joints with non-conductive sealant.






Hopefully this helps.

[minigts]

When it rains it pours. The alt overcharging can certainly kill them quickly. Honestly, running at 16V like you are is a testament to the durability of the components.

Best of luck with the showing!

haha, true. These things can take a beating and keep on ticking as many of us know.

I also had two PMs acting up/go bad. Would short the radio out if I didnt run highbeams everywhere. Car was so much happier with the external I'd just convert any new project td I got.

Yeah, I'm just very anal about wiring and other things, but I may need to go the way of an external regulator if nothing can be done with the PMs I have. (I have two to work with)

The PM regulator is the typical cause poor voltage regulation with the 10 and 14way 'pinch-fingers' terminals and LM terminals next in line.
In the case of a PM failure, the voltage regulator connection (solder joints) are the usually the culprit.
Narrowing it down even further, when the heat sink on the regulator becomes covered with road dirt and/or corroded, it loses thermal rejection capability.
The worst case situation is caused when the PM regulator has dirt covered/corroded heat sinks and no means of airflow (air-box breather tube or other) is being provided.
(see regulator reference pic)

If you open the PM and use oil or WD-40 on the BiWax rubberized coating, it will allow you to see the regulator pins and the solder joints.
Browned, dried, or cracked coating on the backside of the PM, in the area of the regulator OR connector areas, are tell-tale signs of poor connection and the resulting excessive heat.
Dig out the rubberized coating, re-solder the regulator and connector pins as needed, and correct the 'pinch-finger' terminals with a small paper clip or stick pin.
(Note: The round housing of the 10/14way terminals is not the contact area, as seen in the reference pic below, therefore squeezing the round portion of the terminal is an incorrect approach)
Re-seal any repaired solder joints with non-conductive sealant.






Hopefully this helps.

haha!! Ken to the rescue! I'll take a look at my connectors and the PMs to see if there is any maintenance I can do in order to salvage these. I prefer to use the made-for-the-car stuff, but if I can't fix these I'll just have to go to an external regulator. I've considered removing the potting compound and checking or replacing these things. I know it can be done, but just haven't done it.

Thanks for the info Ken, I'll post when I've checked things out.

[cordes]

Give me a buzz if you have any questions regarding removing the potting compound. It's pretty straight forward though.

[supercrackerbox]

I've still got the extra power module you asked about too.