help! voltage surging when cold

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Jordan345

Jordan345

10 Year
Joined
Nov 11, 2011
Threads
22
Messages
390
Location
Kamloops
I'm stumped on this and need help from the forum on this.. i've been searching and come up with nothing. I have a 2001 100 series and with the symptoms -

upon cold start, the engine fires up strong and stays running, but has surges in the voltage - this leads to dimming lights, dash lights and variation in the idle (its still strong and doesn't lope, but i notice the surging in the electrical mostly with some surging in the engine).. I don't mean power, just engine - if that makes sense.. driving is normal, except i still get surging in the voltage/electrical systems until its totally warmed up. the power remains the same throughout this cycle, like i said, just in the electrical and upon idle.

now background - one week ago i replaced the starter contacts and plunger.. first time around i couldn't get it to turn over at all, so i disassembled everything and put humpty dumpty back together.. voila!! worked great.. I then changed the radiator fluid as someone put green crap in there - now its flushed with de ionized water and running on toyota red formula. .since all this was done, it ran fine for about a week.. for some odd reason, the routine i described in the beginning started out of the blue. wierd voltage/electrical loping when cold. I stopped for lunch, parked car for a couple hours, got back in, and it run funny as indicated above.

since then in trying to diagnose, i have replaced the battery an optima red top, replaced 1 out of 4 o2 sensors (not for troubleshooting this, just haven't installed the ones i bought yet). the remaining sensors will go in when i figure this out.

I've gone over the vacuum hoses - they seem fine.. what else could this be? what could cause this behavior? what can i do to further diagnose, treat?

i need some suggestions guys.. btw, i'm a DIY on the truck. i love figuring out these things on my own and having a sense of accomplishment when i get it - i'm a beginner, but have done the OME suspension, starter contacts, serpentine etc.. looking to learn more as i go..

Thanks for the help!
 
i should add - i was thinking this may be the alternator? i understand there is a voltage regulator 'inside' somewhere that may be bad? does this seem like a logical problem area? do these things die in this manner? how do i test this?
 
No dice? Nobody has experienced this or can offer guidance? But I don't want to see the stealer!
 
Jordan I don't have much. But other Mudders may chime in here soon.
 
Unplug the harness to the alternator and start the vehicle to see how the electrical system / engine behaves. Presumably, the engine and voltage will smooth out. Then plug in the alternator harness and if the issue resumes, then it's probably a safe bet that it's somehow alternator related. However, before I'd pull the alternator, I would try grounding the alternator casing directly to the battery negative post. Probably won't change anything, but there's always a chance that your issue is related to bad or flakey grounding. Jumping the alternator casing directly to the battery negative post will rule out that. Once the alternator is out, you can have it bench tested at an alternator/starter shop. Have the brushes and regulator replaced if necessary. Hopefully, when it's reinstalled, the problem will be resolved. If not, maybe somehow the starter rebuild is causing an intermittent shorting issue. Regardless, I don't envy you....chasing down electrical issues can be mind-numbing.
 
Mobi arc

Thanks for the advice on that. I am just back in the country today and will give that a try tomorrow. I am hoping that it is the alternator, as I want to replace with a high output mean green unit. I eventually will be running more acessories off it, so no need to replace later. The current alternator is about at its service life with 123K miles. During the starter install I broke off that stupid grey cap (might ot be so stupid now that I am electrical surging when cold) covering on of the terminals on the starter, but there was no touching to anything near by - I figured for corrosion reasons..

I don t think it would explain the fact the surging goes away when it warms up. Anyways, all guessing at this point until I get that alternator tested. Do you know if i d be screwing anything up by upgrading to a 230 amp - can the alternator fry anything if it's larger than stock? Or reduce life of other components?
 
Crappy spell check and ipad screen keyboard equals poor writing. Sorry guys
 
Jordan345 said:
Mobi arc

Thanks for the advice on that. I am just back in the country today and will give that a try tomorrow. I am hoping that it is the alternator, as I want to replace with a high output mean green unit. I eventually will be running more acessories off it, so no need to replace later. The current alternator is about at its service life with 123K miles. During the starter install I broke off that stupid grey cap (might ot be so stupid now that I am electrical surging when cold) covering on of the terminals on the starter, but there was no touching to anything near by - I figured for corrosion reasons..

I don t think it would explain the fact the surging goes away when it warms up. Anyways, all guessing at this point until I get that alternator tested. Do you know if i d be screwing anything up by upgrading to a 230 amp - can the alternator fry anything if it's larger than stock? Or reduce life of other components?
Click to expand...

I broke off the same gray cap, no problems since. There are a couple ground wires that have to get put back, look at those. Vacuum leak could cause some engine surging, but this sounds like mostly electrical.

I agree with trackmur, look over everthing you touched or might have sat or stood on during the starter job.
 
Sounds like a classic case of the rectifier diode in the alternator starting to go bad. An alternator produces alternating current (thus the name) and the rectifier stops half of the sine wave to create the DC current that the 12 volt system needs. A good parts shop will have a tester that can confirm my diagnosis from afar ....
 
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Much to my annoyance, I took everything apart and back together twice. I can do this with my eyes closed. I dread a third time. I checked all vac hoses - they are on and tight.

Scottm - thanks for validating the lack of cap to causing problems.

Trackmur - are there negative consequences to unplugging the alternator and starting? Further damage? as for problem arising after the starter contact job, it wasn't until a week after the problem started - out of the blue.

Ujz100elkhntr - I don't know squat about the internal workings of the alternator. Your assessment makes sense but I m a noob. If the condition goes away after the true warms up, is your assessment still valid? Even constant aceleration and pedal pressure will cause the cyclical surging of the lights and dashlights.

If testing doesn't work I will shamefully take it to the stealer and he will take my hard earned money.
 
Unplugging the alternator harness prior to starting will not damage the alternator or anything else. The alternator will spin and create no output. If the vehicle still surges, and the alternator is de-powered, then you know it's not alternator related. Your issue could be a bad diode in the rectifier plate, but if you de-power the alternator and still have surging, then it's clearly not a bad rectifier.

Jordan345 said:
Much to my annoyance, I took everything apart and back together twice. I can do this with my eyes closed. I dread a third time. I checked all vac hoses - they are on and tight.

Scottm - thanks for validating the lack of cap to causing problems.

Trackmur - are there negative consequences to unplugging the alternator and starting? Further damage? as for problem arising after the starter contact job, it wasn't until a week after the problem started - out of the blue.

Ujz100elkhntr - I don't know squat about the internal workings of the alternator. Your assessment makes sense but I m a noob. If the condition goes away after the true warms up, is your assessment still valid? Even constant aceleration and pedal pressure will cause the cyclical surging of the lights and dashlights.

If testing doesn't work I will shamefully take it to the stealer and he will take my hard earned money.
Click to expand...
 
^^ X2 what mobi-arc said.

To answer your question directly, yes, it is conceivable that temperature can make the rectifier diode(s) (or rectifier plate) act differently.
 
Hey! Thank you! I went and unplugged the alternator and the problem went away! So, is this diode in the rectifier plate reachable or just easier better to buy a new alternator? I was hoping to replace it anyways with A mean green 230 amp. Have you guys heard about these things? Longevity? Durability? Compared to eom 100 amp?
 
I am not intimately familiar with the insides of the OEM alternator. I have had mean green products on the Heeps I have owned in the past. If it were my money, I'd go with an OEM Toyota part from beno or Cruiser Dan at American Toyota.
 
You can have the alternator serviced at an alternator/starter rebuilding shop. The rectifier can be replaced if it's faulty and if the alternator is open already, change the bearings and brushes as well. Most rebuilds will cost around $100 and the rectifier costs about $30 to $50 depending on the mark-up. If you rebuild it, make sure they test it to verify the alternator has a problem. They may test it and find it's perfectly fine and the problem is in the connections and/or grounding of the alternator. If you don't want to repair the alternator, you can always replace it for a couple hundred bucks. Call WAI (Welcome to WAIglobal Serving the Parts Needs of the Automotive, Heavy Duty, Power Sports Aftermarket - WAIglobal is the preferred parts manufacturer and supplier of alternators, starters, electronics and components for the automotive, heavy duty, ind) and see who resells in your area.


Jordan345 said:
Hey! Thank you! I went and unplugged the alternator and the problem went away! So, is this diode in the rectifier plate reachable or just easier better to buy a new alternator? I was hoping to replace it anyways with A mean green 230 amp. Have you guys heard about these things? Longevity? Durability? Compared to eom 100 amp?
Click to expand...
 
Jordan345 - did you resolve your situation? Did you rebuild/replace/upgrade your Alternator?

Did you ever check the Voltage you were getting at the battery terminals while idling - what kind of surge were you getting?
 
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