DaleMX Posted August 24, 2005 Share Posted August 24, 2005 I also have have the option to run 3 relays and make it a true 2 speed fan. If the fan was already running on low then the current surge going into high would be alot less. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted August 24, 2005 Share Posted August 24, 2005 From my discussion with Mark he recommended hooking the fan directly to an insulated terminal block (which I ordered from him) connected to the output of the alternator (not the battery). He said the alernator puts out around 14 volts while the battery only puts out around 12 volts, Bart, When the alternator is running it's feeding 14 volts to the battery. I know you want to control your fan with the PCM but if all fails use two switches like me; one for hi, one for low. My voltage drops when running on high speed but my idle never varies and everything works real well. Hanns Quote Link to comment Share on other sites More sharing options...
wheelman Posted August 24, 2005 Share Posted August 24, 2005 Bart, I had the feed from my alternator running through the amp guage like you do, at least it sounds exactly like mine used to behave. I rewired it so the alternator feeds the Datsun harness as well as connects directly to the battery and feeds the underhood fuse box. This way the underhood fuse box gets current from the alternator and when it needs more than the alt is putting out it draws from the battery. Mine never does this though as I have the original 140amp alternator from the Caprice cop car. My amp guage rarely moves off the center line now because the fan current is not running through the Datsun harness. I used 3 relays to wire the PCM controls for the fan so the high and low speeds will never be energized at the same time. Before I figured out why the PCM was running the fans all the time I burned up 1 of my high speed fan relays which caused power to be supplied to the PCM even when the key was off, killing the engine required me to let out the clutch while in gear with the brakes locked. Not sure this helped but it might be part of Matt's problem also, check your relays to make sure they are still good. Wheelman Quote Link to comment Share on other sites More sharing options...
clint78z Posted August 25, 2005 Share Posted August 25, 2005 Here is a useful test on the alternator and circuit. http://www.forparts.com/techdiode.htm Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 28, 2005 Author Share Posted August 28, 2005 Thanks to everyone who contributed and special thanks to Clint and Speeder. Finally got a chance to put some miles on the engine today doing a little over 60 miles of in-town driving from 1-4p with lots of stop and go. Highest registered temp was 187* in an area with lot of lights and slow moving traffic. Problem appears to be solved as there is now no surge that affects the electronics and temps are where I feel compfortable. Should get a little better when the fresh shortblock loosens up a little more. Now need to figure how why the O2 sensor is not registering so I can start tuning this puppy. Quote Link to comment Share on other sites More sharing options...
240Z2NV Posted August 28, 2005 Share Posted August 28, 2005 I am a long way from my electrical install but always look forward to the learning experience. My plan is to use the Taurus fan on my LS1 hybrid, as well. I'm curious, and forgive my ignorance, but no one has mentioned the Volvo two speed relay that was also noted in the JTR manual. I was under the impression that the JTR guys were the ones to come up with the Taurus fan recommendation, and the Volvo relay as well. So could any of these problems be from not using that relay or are many of you guys who are already 'there' using the relay as well? Again, I'm a fish out of water with electrical issues; but, trying to learn. I went to alot of trouble to find that Volvo relay, and if it is not going to help with the newer ECU and LS1, then it was just an unnecessary step. The information, albeit mostly over my head, is going to prove useful to me (someday) and others for sure. Quote Link to comment Share on other sites More sharing options...
speeder Posted August 29, 2005 Share Posted August 29, 2005 Hey Scottie, Did you need to use one of my big-A$$ Caps? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted August 29, 2005 Author Share Posted August 29, 2005 Rick, I ended up using the blue Mallory unit because it had the highest rating and fit perfectly in the spot I wanted to use. The one we thought was 80K MFD was actually 30K. Between our 8 eyes we still had trouble distinguishing a 3 from an 8. Then again, it was 11p in a dark parking lot (damn that sounds devious) :D 240Z2NV, are you saying JTR recommends using that Volvo relay with the Taurus fan? Make sure you understand the specs of that relay if you plan on running the GM ECU and voltage-sensitive sensors. That was really the crux of my problem. Quote Link to comment Share on other sites More sharing options...
clint78z Posted August 29, 2005 Share Posted August 29, 2005 Yah !! Glad to hear that the problem has been solved. Scottie had a good grasp on his wiring, it was solid install to begin with. Putting the battery in the trunk can cause small problems eventhough he did use large power cables. The battery itself acts like a buffer, it smooths out AC ripples from the alternator, and buffers momentary spikes due to high load demand like the taurus fan. Clean your battery once a year at least with baking soda, and use dielectric greas on the terminals. This will cut down on corrosion, and give you full voltage. Happy Trails !! Quote Link to comment Share on other sites More sharing options...
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