daltongc

Okay guys, the timing belt change has created a few other issues it seems. During the procedure to access the belt cover, I disconnected the temp sensor from the Y pipe. I was careful to get it back on and everything appears fine. Since I've done this, everytime I start the car, the radiator fans come on at HI spead, I mean ready for takeoff! I read one of the sticky's last night about the cooling system diagram and noticed a bleeed valve reference. I'm wondering if there could still be some air in the system that might cause the sensor not to be working correctly. Also, I am going to clean the contact for the sensor and test that. I've checked the relays and pulled them all and checked them. They appear to be working okay, but when I plug in #2 (the first brown one) the fan speed goes to super-hi. The temp gauge works okay and has the same response it did before the belt change. The heater/defroster is working fine as well with plenty of heat.

Anything obvious I should be checking besides this?

Thanks

kcidmil

How long does the fan stay at that speed? Sometimes the system does a run check when starting up, mine does it. It runs for about 10-20 seconds then shuts down, but that is on first start up when the car is cold.

Wiking

What did u find in u ypipe? Suppose O2.

Check out the wiring diagram for hi speed fan. The circuit does not know about bubbles...

Check the temp sensor and its resistance. Check voltage at ECU.

daltongc

two things.. I probably referred to the Y pipe incorrectly. What I meant was the Y where the radiator hose and the bypass hose connect. No 02 sensor etc as in the exhaust Y pipe. Second, the fans seem to stay at high speed as long as the car is running. They come on at high speed when the car is started cold.

kcidmil

I have to agree with Wiking, check the voltage going through the sensor, and at the ECU. Sounds like the ECU is not adjusting the speed down. Or the sensor is stuck open or fully closed... not to sure without looking at the schematic. And I don't have one in front of me right now. We'd be able to help you further if we know how the system is currently running.

daltongc

okay.. new to Nissan diagnostics. What I thought might have been the problem, the sensor in the radiator Y manifold appears to be ruled out. I checked this by unplugging the connection and found that the temp gauge stopped working and dropped to the bottom. When I reconnect it, the temp gauge returns to the normal operating temp position. The ECU is one of the relays in the group with the fuses etc next to the battery? Also, I noted when working with the temp gauge sender unit that there is another connector on the firewall side of that water manifold. I never had this disconnected. What exactly does it do?

Thanks

daltongc

Wiking, read your site info on ECU/TCU, much wiser now thanks. I'll take a look at mine and see what gives there.

Wiking

VG30E ist for EGRC. That water Y-joint is shown http://www.cardomain.com/memberpage/748507/8

...EGRC is on another page. I think its easer to go through them than through any manual...

daltongc

found that, agreed EGRC. Checked and cleaned the ECU/TCU connections inside the car with battery disconnected. Reconnected everything and nothing has changed. ECU on other side of console still had clear plastic over the adjustment screw. Not sure what else to check now. You mention resistance to pins on the ECU connections. Don't have an ohmeter, but can probably find one. I'm annoyed with the car at this point. I may just sell it and migrate to something newer.

Wiking

The problem is only fan at high rpm? You may disconnect that... A/C might be the problem, IF I now remember right. At least it uses the fan high rpm. Try taking AC relays off; or just any seemingly related.

Five year olds start to have same problems: either u fight through and dont sell, or buy 2003 smtg...

I'll check the circ but bedtime is coming for kids...


Edit: All control for both fan relays 1&2 come from ECU pin 18(relay1) &6. If temp sensor reading for ECU is high, and-or A/C is playing games, this could be the result. relay 3 is high rpm.

daltongc

Wiking, I first noticed the hi fan speed issue when I was finishing up the timing belt install. I had the car running and the fans cam on at high, then surged up and down a little, then quited down. I later turned the AC on to test and the fans behaved. Then I had the issue of the car not starting for whatever reason. I reset the security (?) by locking and unlocking the door with the key, then the car started. Since then, the fans have been permanently on high. What about disconnecting the AC compressor and trying that? Any chance that would do anything?

Thanks for all the input.

Wiking

That first thing is normal operation; it does not happen that way always.

Testing wont harm. I suspect ECU will find it out and either stop the fans and/or puts the check light on. ECU gets input also from the cabin control panel (there is imbedded pcb; actually computer). U say playing with A/C : if there is bad contact or worn switch; or broken component, bad contact?

The fans have two speeds: relay3 gives gnd to fans second high speed windings; thus the speed is variable by ECU. Take relays 2&3 out and you can drive decently until u get that problem shot down...

Security uses the inhibitor relay, gets one input from the door. --->Bypass that relay contact pins under water reservoir; the issue could be in that inhibit circuit (or not). Same bypass -result is if ign sw 4&5 pins are shorted together.

There is still that SMJ junction PITA place behind fuse assembly, at drivers left leg farthest corner. There are two circ breakers, and those big connectors. These are in picture if win/lock/security at door is suspect.

daltongc

Wiking, thanks for the info. I noted that when I was working with the fan relays, the blue one would shut them all down if removed, #3 appeared to control the passenger side fan and #2 was the driver's side. For some reason #2 seemed to run faster than #3. I've been driving the car today and think it's still doing the high fan speed but haven't had time to look. You mention a hinky AC control unit perhaps being the culprit. I had this out and looked it over a few weeks ago because all of the display lights are burned out. I concluded that it was not a "user serviceable" item and put it back in. I did find that the temp control slide had a problem with the contacts that provide current for the **** to illuminate. The **** is broken off on mine, so I didn't worry about it. I have to use a key to make the slide go past the rough spot with the contacts, about 1/2 way through the slide. I noted a microswitch that the lever depresses when you slide it all the way to cold. Not sure what this is all about. I have tried moving the controls back to heat to see if this will change the fan speed, but so far nothing has changed with it.

Will it hurt anything to drive the car with the AC on for a highway trip with the two brown fan relays (#2,#3) removed?

Thanks for all the help

Wiking

T here is a cover on top of the assy, two microlamps under. See stickies for Craigs job as he swapped from manual to auto ctrl. Buy another assy from scrapyard and the problem is solved.
The microswitch is for the all warm air -flapmotor control. U need that at zero temp...

It will not hurt as rushing air cools enough, but engine temp should be kept normal. If relays are in u pocket, needs you as a driver... I would let one fan be ON always (low speed), that definitely does not hurt. No fans: in the summer it will be cooking in city; A/C needs fans also.

Another way: Install a new pair of wires into the cabin, add a switch: use this to manually ctrl the fan(s). Install the wire ends in the fan contanct socket pins.