85"720 Posted July 17, 2014 Report Share Posted July 17, 2014 Relay buzzing loud at a stop but goes away when accelerating. Should I replace it or is it something else. Also battery light is lit but very dim. Quote Link to comment
datzenmike Posted July 17, 2014 Report Share Posted July 17, 2014 Common problem with 720s. For the choke heater to work the alternator must be charging the battery. A reduced charge or voltage and the relay will flutter on and off. Check the fan belt for damage or looseness. Battery posts clean and tight? Quote Link to comment
85"720 Posted July 17, 2014 Author Report Share Posted July 17, 2014 Yes battery posts are clean and belt is new. Maybe alternator dying? Quote Link to comment
datzenmike Posted July 17, 2014 Report Share Posted July 17, 2014 Possibly. New belts tend to stretch right away, maybe check again. Check the fusible links near the positive post. There are three, don't rememner which one if for putting charge back into battery. Clean check the contacts on the plugs, does the wire look melted? Maybe a temp. jumper to see if the light goes out Quote Link to comment
85"720 Posted July 17, 2014 Author Report Share Posted July 17, 2014 I'll check contacts.Belt is 7 months old. alternator has never been changed. So I think it might be the alternator. Quote Link to comment
datzenmike Posted July 17, 2014 Report Share Posted July 17, 2014 Take it in and have it tested for free. The Nissan alternator is worth about $300 new and gives good reliable output and life.A $60 special will give exactly what it's worth. If you do, try to keep the original in case this isn't the problem. Quote Link to comment
85"720 Posted July 18, 2014 Author Report Share Posted July 18, 2014 Ok ill take the alternator in and have it tested. Quote Link to comment
datzenmike Posted July 18, 2014 Report Share Posted July 18, 2014 Sorry I see it's the fuel pump relay then? Both are located above the pass side kick panel. Both need alternator charge to work properly. They both may buzz but the choke relay is usually the cause. The lightly glowing charge lamp isn't normal, and fixing this may kill the buzz. Quote Link to comment
85"720 Posted July 18, 2014 Author Report Share Posted July 18, 2014 Yeah the buzzing noise is right next to the relay. Tomorrow ima get the alternator check. Quote Link to comment
NissanEgg Posted July 18, 2014 Report Share Posted July 18, 2014 Are you sure it's not the fuel pump control module under the right side of the dash buzzing? If it goes out, you can always bypass the module with a homemade jumper harness to make the pump work again. Quote Link to comment
datzenmike Posted July 19, 2014 Report Share Posted July 19, 2014 Fuel pump relay is this thing... The smaller Blue or Brown cubes are the choke heater relay and if an automatic an interlock relay. Usually it's the choke heater relay so put your hand on it and see which one is buzzing. Quote Link to comment
Z-train Posted July 19, 2014 Report Share Posted July 19, 2014 There is also a solder joint in the relay that is known for coming"un-done". Quote Link to comment
datzenmike Posted July 19, 2014 Report Share Posted July 19, 2014 The relay for the fuel pump usually is intermittent or fails. Anything is possible even buzzing. Make sure the alternator is putting out a good charge first. Quote Link to comment
MikeRL411 Posted July 19, 2014 Report Share Posted July 19, 2014 Take it in and have it tested for free. The Nissan alternator is worth about $300 new and gives good reliable output and life.A $60 special will give exactly what it's worth. If you do, try to keep the original in case this isn't the problem. New alternator brushes just might be the cure for your 30 year old alternator depending on your mileage. Get it checked first! Quote Link to comment
Charlie69 Posted July 19, 2014 Report Share Posted July 19, 2014 Had 2 alternators die on my 86 720 and each time I would here a clicking noise coming from the passenger side of the dash. Replaced alternator and clicking noise went away both times. Quote Link to comment
85"720 Posted July 19, 2014 Author Report Share Posted July 19, 2014 Alternator was bad. it did its job All is good now. Thanks guys Quote Link to comment
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