1999 Nissan Quest

Engine Cooling problem
1999 Nissan Quest 6 cyl Two Wheel Drive Automatic 100, 00 miles

I have Nissan Quest mini van 1999, 100: 000 miles.
I have problem with Radiator fan did not turn on low speed when engine warm. The fan turn on only on high speed, or A/c or heat on.
1) I tested the Fan by Jumped the hot wire directed from battery to the fan, It worked.
2) I tested all three relay. Apply power to each invidual, all three clicked
03) I checked power of three terminal, all they have power, when inigtion key was on position.
The problem is there is 7.5 am RAD not power at all. Engine off, or run, the fuse checked ok. There is no power, even engine ran,
The raw of Fan relay A is low speed, B is high 1, C is high 2,
4) I switched relay by one at the time, both B and C high speed worked.
The problem is A relay position not work at all. Runing engine to hot. But relay did not click to close curcuit, so the low speed can turn.
I moved same relay to the other place B and C high speed fan, it worked high speed fan.
The theomastart worked Ok, Coolant sensor worked, It send signal to turn high speed fan on.
Please, Tell me How do you think? Thank yoiu
May 25, 2009.

Hi vicauto2,

Thank you for the donation.

Your problem seems to be Fuse J ( 7.5 or 10 A ) no power supply. It should be hot at all times. Power to it comes from the 140 A fusible link. It could be a fault in the fuse box internal connections.

Try attaching a remote wire to the the fuse and apply battery voltage to test if the slow speed works.

Check the # 44 Fuse. It also works the fans.

May 25, 2009.
I'm very sorry, I've tried to Jump the fuse, but it was burnd up, both ground jumping wire and underthernet of the fuse, just right engine started.
I jumped from 7. 5 A terminal fuse to baterry with the fuse holder and 7.5 fuse on it, between terminal and battery on hot wire.
I checked the fuse there was power on the fuse, with inigtion key to Acc position. I started to warm up engine to see how the fan is going. But just after started the smoke raise up. I have to stop immidiately. It melt negative wire and burn up the wire from terminal.
Please ! Tell me what did I do wrong? Or some thing grounded. Apply voltage to terminal it burn up.
I could not find the way to jump from 140A fuse. So I have to jump directly to battery, The Amp of battery is about 90 to 100 amp.

May 26, 2009.
You bypased the 7.5A fuse and that is the cause of the wires burning up as there was a shorting somewhere.

I have some varied data and would like to confirm this.

Where is the location of the 7.5 A fuse that you are refering to?

May 27, 2009.
Hi !
7.5 A fuse is beside of relay A as low speed fan relay. It was same box of 3 Fan relay in engine comparment
As the first question email, I told you that, There was not voltage in this fuse, and in this socket, You told me Jump the fuse, Then it burned.
Please, Tell me How to Jump the fuse? And use some thing test out side the car first, otherwise this could happen again , Thank you

May 27, 2009.
After some research I managed to get the testing procedures for the cooling fan circuits.

1. Check Low Speed Fan Operation
Ensure coolant level is okay. Turn ignition off. Disconnect cooling fan relays No. 2 and 3. See Fig. 6 . Start engine. Set A/C temperature control lever to full cold position. Turn A/C switch and blower fan switch on. Run engine at idle for several minutes. Cooling fan should operate at low speed. If cooling fan does not operate, go to next step.

2. Check Power Supply (Low Speed)
Turn ignition off. Disconnect cooling fan relay No. 1. Turn ignition on. Measure voltage between cooling fan relay No. 1 harness connector terminals No. 1 (Blue wire) and ground, and terminal No. 5 (White/Blue wire) and ground. See Fig. 7 . If battery voltage is present, go to next step. If battery voltage is not present, check fuse No. 29 (10-amp) and fusible link (75- amp). If fuse and fusible link are okay, check open in circuit between fuse block and relay.

3. Check Ground Circuit (Low Speed)
Turn ignition off. Disconnect cooling fan motor harness connector. Using ohmmeter, check for continuity between fan motor harness connector terminal No. 2 and fan relay No. 1 harness connector terminal No. 3 (Blue/White wire). If continuity does not exist, repair open in Blue/White wire. If continuity exists, check for continuity between fan motor harness connector terminal No. 3 (Black wire) and ground. If continuity exists, go to next step. If continuity does not exist, repair open or short in Black wire.

4. Check Output Signal Circuit (Low Speed)
Disconnect ECM harness connector. Check for continuity between ECM harness connector terminal No. 38 and fan relay No. 1 connector terminal No. 2 (Blue/Orange wire). If continuity does not exist, check repair open in Blue/Orange wire. If continuity exists, go to next step.

5. Checking Cooling Fan Relay (Low Speed) Remove cooling fan relay No. 1. Apply 12 volts and ground to relay terminals No. 1 and 2. See Fig. 7 . Check for continuity between relay terminals No. 3 and 5. If continuity does not exist, replace relay. If continuity exists, go to next step.

6. Test Cooling Fan Motor (Low & High Speed)
Disconnect cooling fan motor harness connectors. Connect positive battery voltage to fan motor terminal No. 2 and ground to fan motor terminal No. 3. Fan motor should operate at low speed. Connect battery positive to fan motor terminal No. 1 and negative lead to fan motor terminal No. 3. Fan motor should operate at high speed. If fan motor does not operate as described, replace fan motor. If fan motor is okay, check ECM pin terminals and/or wiring harness connectors for corrosion and damage. Repair or replace as necessary.

Do the above test and see what you come up with.

You mentioned the fuse was ok but did not have power to it. It should not have shorted. For testing of circuits, it is best to test with intermittent touching the contacts to confirm if it is horting first and the point of contact should be at the power source and not the component side.

May 28, 2009.
HI, sofar I have checked continuity the socket relay 1 and fan connector have have continuity on tetminal 1 and 5.
I have proplem on step 4 ( Check signal out put from ECM )
Is the ECM location on the right site( passinger site)
between AC evamperator and the Air bag?
Do I hve to remove ECM test it? If I have to, Then
Please ! Tell me instruction how to remove?
The way I see I could remove AC evamperator, disconnect AC hoses to access to ECM is very pain.
Do I have to kill my AC?
Is any scan or intrument hook up ECM can tell some open in there? It 's very expensive, worse thing is replaced it, but not fix the problem, loosing money.
Please, tell me any thing you know about ECM testing, removing, e.T . Thank you

May 31, 2009.
There are diagnostic equipment that can be plugged in test the various circuits but these are rather expensive items.

The ECM is located behind right side of dash. Removal of the ECM would facilitate testing and AC components need not be removed.

Removing the glove box should allow you to access the ECM. I do not have much info on the ECM removal except the view of the instrument panel.

May 31, 2009.
Hi, I have one more trouble for ECM remonving,
I disconected battery removed Air bag, so I can have some room to ECM, But I could not get ECM out yet,
I Put Air bag back with conection, and I tried to start, But Engine did not start, and Air bag light is flasing,
please, some one know How to set it back to normal , and what did I do wrong? Please tell me.
Thank you very much

Jun 9, 2009.
Recheck the wire connections, look out for loose connectors. Check if any ground wire had been loosened and not retightened.

Removal of battery could cause the securrity system to be armed when reconnecting. Try closing all doors and using the key to lock and unlock the doors.

Jun 10, 2009.
Hi ! Sofar I did not have any lucks, the problem got serious, I could not find any loosing connection, I put back the same way out, Just plug 2 white pin and power connection, That is it.
The Air bag is still flashing, engine could not start.
I hooked up scan OBD II, But It could read any thing in ECM. Alway said LINK ERROR.
When I removed ECM, I loose the srcew at the back that holding all the connection, But I could get ECM out, then I tighted It back,
Now, Air bag did not inflate, but flasing, Engine didi not start, Scan OBD II could not read ECM. Very frustrated,
Do you know any diagnostic tool can read this problem? Or how to fix these thing?
I need your helps, any helps will great apreaceation.

Jun 10, 2009.
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