QuestionRecently my maxima overheats while in traffic and when I checked I saw one fan working with very low speed, however couldn't overcome high temperature.I took the car to dealership and they diagnosed as fan control system problem, they changed the fan and control cooling fan but they couldn't fix it, they said it also needs to change the ECU which cost about $1000. After fan replacement the new fans don't work with very low speed anymore, I noticed that when the A/C is on two fans work with high speed ( Just with A/C on).
We really doubt about dealership diagnosis capability, we need some expert just to confirm that the source of the problem can be ECU and this is a right diagnostics and we should change the ECU?
this is the dealership report
“265441 VEHICLE OVERHEATS FAULT CONFIRMED,VEHICLE OVERHEAT AT IDLE,HOOKED UP CONSULT AND FOUND THAT AT 97 DEGREES CELSIUS THE COOLING FAN DOES NOT COME UP.IN ACTIVE TEST,TRIED TO TURN ON COOLING FAN BUT WAS INOP.RECOMMEND NEW COOLING FAN /SWITCH AFTER INSTALLING NEW COOLING FAN FOUND THAT IT WA STILL INOP.CHECKED POWER AT COOLING FAN RELAY 1 ,GOOD.CHECKED GROUND,GOOD.CHECKED CONTINUITY FROM ECM TO RELAY ,GOOD .SUSPECT FAILURE TO BE IN ECM.ECM CONTROLS GROUND CIRCUIT FOR RELAY .DECIDED TO GROUND RELAY TO BOSY OF VEHICLE TO CONFIRM ECU FAULT.AFTER GROUNDING FANS COME ON.DOUBLE CHEKCED OPERATION OF OLD FAN ASSEMBLY ,NO GOOD .VEHICLE NEED ECM.$1000+TAX TO REPLACE ECU ”
AnswerParnak,
I would get one from a wrecking yard if they are trying to take you for a grand to replace it. With a used ECM you will be in business. Otherwise, you could to the cheap thing and get your own temperature switch and use that to ground the relays at a temperature you set. Checker sells one for a Volkswagen for $50 bucks and it is just a matter of wiring it up and setting the temperature the fans come on.
