Had my kid hold it at 3000rpm
Hangs around 170-180 a lot but got a couple bumps up to 199amps
Hangs around 170-180 a lot but got a couple bumps up to 199amps
What did you do to your NNBS GMT900 Tahoe/Yukon Today?
- Thread starter phattyford
- Start date
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mattbta
Full Access Member
My Mechman 240a orange tag test results say 161a at 800 idle. I'm currently diagnosing with them, because on my NBS Tahoe at idle (525) with engine cooling fans on high and hvac blower on high, I drop down to low 12V at both alternator and battery. It did this with the stock 145a alt, so I got the upgraded one. Put on 1/0 charge cable and 4 different 1/0 grounds when installed. Doesn't matter if I have the 700w fans in or the 500w....tried both. Battery is new. I live in Texas, so no rust, but cleaned all grounds regardless. I need the HVAC at full due to said Texas. Even jumped the positive alt post to the alt turn on pin and still low 12's while talking with Richard @ Mechman.
Will get around to my own thread, just wanted to say i'm jealous. I should get an ammeter, too,
That last test was with everything on as well, front and rear ac on high, seat coolers, rear seat heaters, defroster, wipers, headlights, fogs, steering wheel heater, radio & amp, hazards, radar detector and dashcam. only thing I didn't have on was the rear wiper
thats wild.. any idea what's pulling 200 amps? that's seems massive.
my little car didn't budge when revved up. seems 100 was all it needed.
man I forget what my yukon inverter maxes out at on the 12v side, but I'm pretty it was less than 200amps haha. and that's with a 40amp electric tranny pump running off it. you definitely got some load there.
I'm guessing you've upgraded all the wiring?
mattbta
Full Access Member
20% off and same day delivery for Chinesium = $26. Thanks!
My Mechman 240a orange tag test results say 161a at 800 idle. I'm currently diagnosing with them, because on my NBS Tahoe at idle (525) with engine cooling fans on high and hvac blower on high, I drop down to low 12V at both alternator and battery. It did this with the stock 145a alt, so I got the upgraded one. Put on 1/0 charge cable and 4 different 1/0 grounds when installed. Doesn't matter if I have the 700w fans in or the 500w....tried both. Battery is new. I live in Texas, so no rust, but cleaned all grounds regardless. I need the HVAC at full due to said Texas. Even jumped the positive alt post to the alt turn on pin and still low 12's while talking with Richard @ Mechman.
Will get around to my own thread, just wanted to say i'm jealous. I should get an ammeter, too,
do you have the 2 wire pwm alternator too? or something else.
I'm just interested because you said they had to jump, I've not heard of that. I'm currently waiting on a part now that should put out the request the bcm normally sends to the ecm to start controlling voltage. (my car doesn't work that way) if there was a way to jump something it would save me the hassle.
if you have the 2 wire you could also try picking up the 100$ one iamdub got to try. they seem pretty good.
I have the 230a standard pulley it's been installed for about 3 years now I guess. I did upgrade the charging cable to 4 gauge (I think) had a shop make the cable for meMy Mechman 240a orange tag test results say 161a at 800 idle. I'm currently diagnosing with them, because on my NBS Tahoe at idle (525) with engine cooling fans on high and hvac blower on high, I drop down to low 12V at both alternator and battery. It did this with the stock 145a alt, so I got the upgraded one. Put on 1/0 charge cable and 4 different 1/0 grounds when installed. Doesn't matter if I have the 700w fans in or the 500w....tried both. Battery is new. I live in Texas, so no rust, but cleaned all grounds regardless. I need the HVAC at full due to said Texas. Even jumped the positive alt post to the alt turn on pin and still low 12's while talking with Richard @ Mechman.
Will get around to my own thread, just wanted to say i'm jealous. I should get an ammeter, too,
I have dual batterys in parallel and 2 extra 0 gauge grounds. both batterys go to the starter and I have both grounded together. everything works fine
I was fighting with the rvc previous to getting the mechman thought it was the alternator but turned out to be a bad battery it would show 12v but it's wasn't charging correctly and would cause the rvc to read incorrectly and not bump the voltage up
mattbta
Full Access Member
My 2004 NBS is a 4 pin (but only has three wires) and no RVC.
I see there are some two-to-four adapters. Wonder if there’s harm trying out an OEM 160 or 220 like you mention?
what does it do when you run just the 1 pin with 12v excite, running just the one pin will throw the light on the dash but alternator will be working
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Looks handy for large amp readings, but the jaws are too large for reading the small values for parasitic draws. Too bad the specs aren't clear for DC current limitations.
ya I read the reviews about that one guy said it wasn't going to work for low draw and another said it did
iamdub
Full Access Member
I read that those adapter harnesses don't really do anything but adapt the physical harness and only connects one of the functions. You can replace the regulator inside with the correct pins, though. Requires very little, but easy modding for fitment and minor soldering.
mattbta
Full Access Member
That’s what Mechman had me do. Knew it was excited because it hummed a bit, but still only low 12v under high load. Super weird because I’m 100% OEM electric wise aside from the electric fan conversion, and obviously the upgraded wires for the Mechman. I’ll start a thread in a bit in the NBS section. Sorry all!
I got one of these a few years back when they were about $125 but from eBay. They'll do the low DC current measurement with the small jaw, but it's only a 1/2" hole. Worked great to find a few parasites...
Electronic Specialties 687 Low Current Probe Digital Multimeter | eBay
Find many great new & used options and get the best deals for Electronic Specialties 687 Low Current Probe Digital Multimeter at the best online prices at eBay! Free shipping for many products!
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oh, on a side note. I stumbled onto a box that will take a normal relay turn on trigger and use it to put out a pwm for brushless fans. it's not really adjustable but it will take the low signal and put out like a 30% and then high be 100%. I know the normal trucks only have 2 speeds but mine has 3 and the box does up to 3, so I'd get a low med high. and those points are adjustable with hp. so with this crazy tx heat it got me thinking about finding a setup of newer brushless fans from one with a high tow rating and see if they bolt on. I'd guess if you found the right part number or rpo code they would be cheap oem take offs on eBay.
should cool better for less power drain than my old brushed ones. box isn't cheap thou.
should cool better for less power drain than my old brushed ones. box isn't cheap thou.
are they going to warranty it? or did they say to send it in for repair? I don't think they have much of a warranty period but they will repair themThat’s what Mechman had me do. Knew it was excited because it hummed a bit, but still only low 12v under high load. Super weird because I’m 100% OEM electric wise aside from the electric fan conversion, and obviously the upgraded wires for the Mechman. I’ll start a thread in a bit in the NBS section. Sorry all!
mattbta
Full Access Member
Richard said they would warranty it, but I’m not 100% certain it is the alternator since the 19 year old OEM one does the same. Still have to pay shipping and be back on OEM while I wait.
ahh.. yeah, it won't really work. correctly for you.. it would default to 13.7v at the terminal and not reference anything. I don't know. about the check. engine light thou.. the mechman is probably the better bet.
the newer 220am ones, I haven't found anyone that sells the regulator swap from 2pin pwm (I think they are calling these hairpin style because of the rear fins) to the old school ones, only the older style alternators but they do sell a stand alone back that you can adjust the pwm from and set the voltage you want. it's about 80$ or so.. or can be made for 20$ from ebay parts diy.
I didn't realize you had the older style.
since you gotta send it back, if you did find a cheap used one like iamdub got(and found me) , this would be what would control it.
Voltage PWM controller based on Internally Regulated Alternators PCM CONTROLLED 05+ GM vehicles
This is a voltage knob made for PCM controlled 05+ GM vehicles with the small rectangular 2 pin plug. It makes it plug and play with the GM 2 pin harness. There is no splicing of your stock plug required. These are generally in stock and ship within a couple of days of purchase. They work on up...
brand-x-electrical.myshopify.com
