megatron Posted January 31, 2017 Share Posted January 31, 2017 (edited) I have problem Getting a Fan drive to Work after serpentine belt broke and take Fan control wires with it. I fix the wires butt now its engaged all the time. Check for 12V and other wires for 5V its not getting any, all wires are dead No codes, butt if I pull fuse out I'm having code for "fan output" if anybody can help me troubleshoot this thing its a Behr fan drive Thanx Edited January 31, 2017 by megatron Quote Link to comment Share on other sites More sharing options...
Mackpro Posted January 31, 2017 Share Posted January 31, 2017 Heres some info on it. Behr fan clutch AC engines.pdf Quote Link to comment Share on other sites More sharing options...
megatron Posted January 31, 2017 Author Share Posted January 31, 2017 (edited) Thank you Mackpro, look like I will have to do several testing to this drive to determine what happened to this drive or harness. I think at the time belt cut the harness something get shorted.... I just don't understand how come there no any codes? Edited January 31, 2017 by megatron Quote Link to comment Share on other sites More sharing options...
megatron Posted February 1, 2017 Author Share Posted February 1, 2017 Can't find nothing wrong, unless some sensor keeping fan on. At a time this happens with a belt I move truck of the road and trying to keep eng temp below 220 so don't know if I mess up a sensor or something butt I don't know how to check sensor unless I hook comp to it that I don't have Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 2, 2017 Share Posted February 2, 2017 All the Tech's here have made a jumper harness that puts 12 volts and ground to the fan itself. If you run engine for 10 minutes with jumper installed , fan should disengage. Even when this fan is working correctly, it could take 15 min to disengage in very cold weather. Fan should never be locked solid. IF you cant turn fan without slipping the pully on the fan belt then the fan clutch is locked solid and you have to replace it. Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 2, 2017 Share Posted February 2, 2017 Fan disengage harness Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 2, 2017 Share Posted February 2, 2017 Mack wiring diagram. The "fan clutch sol" you see in the pic is just a connection for Horton air fan and not used on your truck. scan0399.pdf Quote Link to comment Share on other sites More sharing options...
megatron Posted February 6, 2017 Author Share Posted February 6, 2017 (edited) It shut of with 12V direct input, now I don't know what to do, is there any way to check if any sensor keeping it on? Everything worked fine before belt broke and cut Fan Drive harness. I need advice Edited February 6, 2017 by megatron Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 6, 2017 Share Posted February 6, 2017 With the old Mack software , we usually go into switch status and see if the fan is commanded "ON" and also if the AC switch says on. Also the intake manifold temp sensor, if its over 175 it will command the fan on. Quote Link to comment Share on other sites More sharing options...
megatron Posted February 7, 2017 Author Share Posted February 7, 2017 That's what I just think about, I check all procedure troubleshooting and nothing wrong unless wrong info getting in ECU and that's why it's on. Will plug a comp on it and find out I guess. Quote Link to comment Share on other sites More sharing options...
megatron Posted February 7, 2017 Author Share Posted February 7, 2017 That's what I just think about, I check all procedure troubleshooting and nothing wrong unless wrong info getting in ECU and that's why it's on. Will plug a comp on it and find out I guess. I hope I can find a problem, fuel mileage drops fast with fan on... thanx Mackpro your info where really helpful now I understand this Visco thing a lot better than when I started messing with it Quote Link to comment Share on other sites More sharing options...
Mackpro Posted February 7, 2017 Share Posted February 7, 2017 Always remember that these Behr fans never totally unlock and free wheel like an air fan clutch. Also they should never be totally locked solid like an air fan as well. If the clutch/fan is locked solid to the pulley and the only way to turn the fan is to slip the belt then the fan clutch is bad and needs to be replaced. Also in cold weather it can take quite a while for them to disengage . Quote Link to comment Share on other sites More sharing options...
megatron Posted February 7, 2017 Author Share Posted February 7, 2017 (edited) This is going to be one hard to find since we check everything OK , the only questionable item was FAN speed sensor.... butt no Foult Code by ECU. Pin No5 don't have 12V or any power, since harness is checked OK the only 2 things can be wrong. Something burn inside ECU at a time that belt broke and cutt a Fan wires, or this ECU need a good Fan Speed sensor reading to activate Power to operate Fan drive. Actually I can't get info of how this ECU is programmed and what Parameters it need to do it. Does it control Ground and hot wire or just ground ( all wires coming out of ECU) Only test I can try is Feed 12V on the pin No5 together with harness connected and see how ECU will respond... 😩😩 or take truck to dealer and ... and... just tell them to fix it $$$$ I will change my Megatron to Behr Mack Fan drive EXPERT I WISH I newer sold my dear 99 Mack CH613 with almost 2mil miles on it was a Champion of roads Edited February 7, 2017 by megatron Quote Link to comment Share on other sites More sharing options...
megatron Posted February 10, 2017 Author Share Posted February 10, 2017 If MackPro doesn't know than I'm selling this Bulldog 😂😂 Quote Link to comment Share on other sites More sharing options...
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