creyc Posted February 7, 2009 Report Share Posted February 7, 2009 (edited) I just installed my MechMan Rhino alternator in my '01 Chevy blazer and changed the belt out at the same time. The old stock CS130D was on its last leg but still putting out decent power despite visibly burned copper inside and a slight grinding noise from the bearing. Idle voltage was a somewhat steady 14.3v however. With the new mechman alt in place I'm reading around 13.5v, regardless of RPMs. (800-4000) The Dyno sheet that came with the alt says Voltage set point: 14.3. Why am I seeing mid 13's if it's set to 14.3? All these readings are without excessive loads, just interior lights and fan running, SAZ-3000D on but not playing, and Kinetik HC1800 in the back. Edited February 7, 2009 by creyc Quote 2001 Chevy Blazer (2) SAZ-3000Ds (2) custom 18" Madmax subs in a second row wall Rockford 600-4 Pioneer PRS components Pioneer P800PRS deck Link to comment Share on other sites More sharing options...
Andrew2944r Posted February 7, 2009 Report Share Posted February 7, 2009 Try cleaning the connection between the Alt and the factory plug, might be dirty... Quote Team Ampere Audio Link to comment Share on other sites More sharing options...
creyc Posted February 7, 2009 Author Report Share Posted February 7, 2009 Try cleaning the connection between the Alt and the factory plug, might be dirty... Not the ring terminals, but the connector plug correct? I will try this. As for the ring terminals, they are brand new so I doubt that would be the issue. By the way these readings are also "cold". Actually right after installing... Quote 2001 Chevy Blazer (2) SAZ-3000Ds (2) custom 18" Madmax subs in a second row wall Rockford 600-4 Pioneer PRS components Pioneer P800PRS deck Link to comment Share on other sites More sharing options...
creyc Posted February 7, 2009 Author Report Share Posted February 7, 2009 On my Blazer this connector only has 2 pins, they mate up with the green and yellow on the adaptor harness that came with the alt. From the Mechman site regarding this adaptor harness wiring: Blue “S” ( external voltage sense) Green “F/I” (signal going to computer) or if using the terminal as “I” then connect it directly to a switched 12 volts Yellow “L” ( to dash light for alternator turn on) I unplugged the connector completely and fired up the truck. Perfect 14.6v regulation at idle. Plug in the harness, drops down to mid 13s. I tried just connecting each individual color, the yellow wire does nothing to affect my voltage, but the green wire is what triggers the voltage drop. Why is this? I measure 12.5v on this green wire from the CAR, odd because I don't measure 12.5 anywhere with the engine running. Any suggestions? Quote 2001 Chevy Blazer (2) SAZ-3000Ds (2) custom 18" Madmax subs in a second row wall Rockford 600-4 Pioneer PRS components Pioneer P800PRS deck Link to comment Share on other sites More sharing options...
Andrew2944r Posted February 7, 2009 Report Share Posted February 7, 2009 Good question man, That voltage reading is way too low if you do not have a load on the Alt, maybe the regulator got damaged while shipping... I would call Mechman he might have a easy solution. Quote Team Ampere Audio Link to comment Share on other sites More sharing options...
bobonit Posted February 7, 2009 Report Share Posted February 7, 2009 I would make sure your belt is tight enough. I had the same problem when I installed my DCPower 250a alt. I was only getting around 13.5 volts even with a MLA installed. After tightenig down the belt, it went right up to 15.6 volts. A telltale sign would be if you hit the throttle while looking at the voltage, does the voltage drop a little when you rev it? If it does, you definitely have a slipping belt. Quote 97 Maxima SE Bunch of shit going in, check out the build Build Log Link to comment Share on other sites More sharing options...
creyc Posted February 7, 2009 Author Report Share Posted February 7, 2009 (edited) Possible, but when I first installed the alt with my old belt, and then after swapping for the brand new belt I still get the same voltage readings. And remember this is without much of a load on the alternator, so it should spin fairly easily without slipping the belt. I will consider replacing the tensioner however, although I don't think thats the issue here. I think it has something to do with the wire harness, and the circuits they're connected to. There are two wires on this harness. The 'L' wire appears to be for the battery light on the dash, which is lit while operating on battery power and SHOULD go out when the engine is running and alt is powered. This circuit is also commonly used to excite the field inside the alternator in order to turn it 'on', but I can't verify this on my truck yet. I'm still not sure if the 'I/F' wire on my Blazer operates in I or F mode. If it's 'F' mode then this wire goes to the positive field inside the alternator to turn it on. This makes sense because I measured 12.5v on this pin when the key was on "run". I'm still not sure how 'I' mode would work so I will continue my research. It seems like my truck is operating in one mode, and the alternator is expecting the other one. I think there is a variable voltage sent to the rotor field to control alternator output, which with the wrong voltage could theoretically reduce or disable the output of the alternator. A schematic of the MechMan alt would help of course but I doubt they would have those available for our viewing pleasure. Nothing is ever truly plug and play, is it? lol Edited February 7, 2009 by creyc Quote 2001 Chevy Blazer (2) SAZ-3000Ds (2) custom 18" Madmax subs in a second row wall Rockford 600-4 Pioneer PRS components Pioneer P800PRS deck Link to comment Share on other sites More sharing options...
MECHMAN Posted February 9, 2009 Report Share Posted February 9, 2009 Possible, but when I first installed the alt with my old belt, and then after swapping for the brand new belt I still get the same voltage readings. And remember this is without much of a load on the alternator, so it should spin fairly easily without slipping the belt. I will consider replacing the tensioner however, although I don't think thats the issue here.I think it has something to do with the wire harness, and the circuits they're connected to. There are two wires on this harness. The 'L' wire appears to be for the battery light on the dash, which is lit while operating on battery power and SHOULD go out when the engine is running and alt is powered. This circuit is also commonly used to excite the field inside the alternator in order to turn it 'on', but I can't verify this on my truck yet. I'm still not sure if the 'I/F' wire on my Blazer operates in I or F mode. If it's 'F' mode then this wire goes to the positive field inside the alternator to turn it on. This makes sense because I measured 12.5v on this pin when the key was on "run". I'm still not sure how 'I' mode would work so I will continue my research. It seems like my truck is operating in one mode, and the alternator is expecting the other one. I think there is a variable voltage sent to the rotor field to control alternator output, which with the wrong voltage could theoretically reduce or disable the output of the alternator. A schematic of the MechMan alt would help of course but I doubt they would have those available for our viewing pleasure. Nothing is ever truly plug and play, is it? lol Your vehicle should be plug-n-play. Did you order the CS 144 adjustable voltage unit, or the fixed voltage AD244 unit? You should be in the 14 volt range in either case. Thanks Matt Quote 1-888-MECHMAN www.Mechman.com [email protected] Link to comment Share on other sites More sharing options...
creyc Posted February 10, 2009 Author Report Share Posted February 10, 2009 I ordered the alt from the GM inventory reduction sale It has a red heatsink on the back, so I'm assuming it's the CS 144 adjustable unit? I talked to (maybe you?) on the phone today, and was told it will run fine without the harness connected. Here she is: It seems to be UN-plug-n-play. I'm at 14.4v steady without the GM harness. Unfortunately with the annoying dash light however. Trying to find a way around this.. Quote 2001 Chevy Blazer (2) SAZ-3000Ds (2) custom 18" Madmax subs in a second row wall Rockford 600-4 Pioneer PRS components Pioneer P800PRS deck Link to comment Share on other sites More sharing options...
ISO Posted February 10, 2009 Report Share Posted February 10, 2009 I didn't know about the built in adjustable voltage regulator until I got mine the other day. I think its cool as hell and it will allow me to remove another electrical component, which is always a good thing. Installed mine the other day but haven't done my thread yet. Quote Isobaric - Refers to the practice of coupling two drivers together to make them act as one. "Giving up doesn't always mean you are weak; sometimes it means that you are strong enough to let go." Insanity: doing the same thing over and over again and expecting different results. The Destruction of a person builds character. Link to comment Share on other sites More sharing options...
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