fan question.
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fan question.
been hunting this past weekend and when climbing hills at 15mph, rpm at 1800 the fan is only spinning 680 rpm until it reaches 208,then the fan comes on and it cools back down to 190,then it starts all over again.even when im driving at 55 and have to go uphill and get into it the temp will reach 202,this is with ambient temp of 80-90*.oil temp is always within 8* of coolant temp.i was under the impression the fan came on in stages.once it comes on its turning between 3800-5000 rpm.but below 208 its only turning 600-750 rpm.should add that the hill we were climbing to get to the hunting spot was around 10-15% and probably 8 miles long.
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that's what I'm missing.its all or nothing with it.I thought it progressed from 195 to 208.its almost like a temp sensor with the low side not working,there's no in between with it.somethings not quite right with it.
Hotshot
Joined: Apr 2010
Posts: 19,055
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From: Saratoga Springs,UT
and Like if Im crusing along and the fan is at 400FSS and I turn on A/C it will step to 600FSS in stop and go traffic it will step back to 400FSS if I get speed above 35-45 mph on a ambeint 95* or less day
95* and up ambeint day everything steps a couple 100sFSS
218 ect fan Will hit 1400-1600FSS
95* and up ambeint day everything steps a couple 100sFSS
218 ect fan Will hit 1400-1600FSS
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Lead Driver
Joined: Sep 2007
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From: Scio, OR
I wouldn't assume that every PCM strategy would operate the same way. Over all the model years with all the updates there were a lot of different strategies.
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and Like if Im crusing along and the fan is at 400FSS and I turn on A/C it will step to 600FSS in stop and go traffic it will step back to 400FSS if I get speed above 35-45 mph on a ambeint 95* or less day
"
95* and up ambeint day everything steps a couple 100sFSS
218 ect fan Will hit 1400-1600FSS
"
95* and up ambeint day everything steps a couple 100sFSS
218 ect fan Will hit 1400-1600FSS
Hotshot
Joined: Apr 2010
Posts: 19,055
Likes: 235
From: Saratoga Springs,UT
at 208ECT the thermistste isnt even fulley open yet
I wouldnt think Fan would kick into high untill 218ECT when the thermistate is fulley open
does your coolant temp sensor read Erratic
sometimes my TFT sensor will read erratic as it warms up
fan clutch harness ok fulley plugged in an no wire chaff at the connector not corroded inside
just thinking out loud
you wont have to worrey about overheat anyway
does it do it on the HWY too
Hotshot
Joined: Apr 2010
Posts: 19,055
Likes: 235
From: Saratoga Springs,UT
<TABLE style="WIDTH: 278pt; BORDER-COLLAPSE: collapse" border=0 cellSpacing=0 cellPadding=0 width=371><COLGROUP><COL style="WIDTH: 278pt; mso-width-source: userset; mso-width-alt: 13568" width=371><TBODY><TR style="HEIGHT: 30.2pt; mso-height-source: userset" height=40><TD style="BORDER-BOTTOM: #f0f0f0; BORDER-LEFT: #f0f0f0; BACKGROUND-COLOR: transparent; WIDTH: 278pt; HEIGHT: 148.55pt; BORDER-TOP: #f0f0f0; BORDER-RIGHT: #f0f0f0" class=xl66 height=197 rowSpan=6 width=371>Engine temperature is not the only parameter that the PCM monitors to determine cooling fan operation. This is the reason that you will see some variation in engine temperature as it correlates to fan operation. The operation/description of the FSS (Fan Speed Sensor) from the PC/ED manual has a fairly good explanation as to how the system "thinks". This is not your traditional engine hits temp X and the fan clutch locks up. The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor the sensor input and control the VDF speed based upon engine coolant temperature (ECT), transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF.</TD></TR><TR style="HEIGHT: 67.35pt; mso-height-source: userset" height=89></TR><TR style="HEIGHT: 12.75pt" height=17></TR><TR style="HEIGHT: 12.75pt" height=17></TR><TR style="HEIGHT: 12.75pt" height=17></TR><TR style="HEIGHT: 12.75pt" height=17></TR></TBODY></TABLE>
just some more info I came across
just some more info I came across
Elder User
Joined: Aug 2010
Posts: 675
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From: NV
This last week I drove 1700 miles pulling a 5 k camping trailer (dry) and a good load in the truck bed. Maybe 14.5 k total?
NV, AZ, NM and back with around 100 degree F ambient. Pulling long hills the ECT would rise to 216 F and then the fan would kick in. The ECT would drop to about 214 F and the fan would drop out. The exhaust temperature was in the low 1200 range.
NV, AZ, NM and back with around 100 degree F ambient. Pulling long hills the ECT would rise to 216 F and then the fan would kick in. The ECT would drop to about 214 F and the fan would drop out. The exhaust temperature was in the low 1200 range.
New User
Joined: Jun 2011
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I am trying to figure out why my truck is puking. It's been to the shop 3 times, all the normal stuff is fine, good egr, gaskets seem fine. They thought maybe it was chip. Pulled chip and still puking. mainly when i tow my trailer (about 6K). I think it may be the fan not coming on properly. Since I pulled the chip I haven't been able to monitor anything. What was happening before was truck was getting up to 220, then 230 on hills and towing. I can hear when it starts puking out the reservoir. Do you guys have any thoughts? Does the stock system have a "strategy"? I'm going to hook my trailer up and take it to the shop since they can't duplicate problem without load. Would PCM need reset? Thanks.
Elder User
Joined: Aug 2010
Posts: 675
Likes: 1
From: NV
I am trying to figure out why my truck is puking. It's been to the shop 3 times, all the normal stuff is fine, good egr, gaskets seem fine. They thought maybe it was chip. Pulled chip and still puking. mainly when i tow my trailer (about 6K). I think it may be the fan not coming on properly. Since I pulled the chip I haven't been able to monitor anything. What was happening before was truck was getting up to 220, then 230 on hills and towing. I can hear when it starts puking out the reservoir. Do you guys have any thoughts? Does the stock system have a "strategy"? I'm going to hook my trailer up and take it to the shop since they can't duplicate problem without load. Would PCM need reset? Thanks.
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I am with ya
at 208ECT the thermistste isnt even fulley open yet
I wouldnt think Fan would kick into high untill 218ECT when the thermistate is fulley open
does your coolant temp sensor read Erratic
sometimes my TFT sensor will read erratic as it warms up
fan clutch harness ok fulley plugged in an no wire chaff at the connector not corroded inside
just thinking out loud
you wont have to worrey about overheat anyway
does it do it on the HWY too
at 208ECT the thermistste isnt even fulley open yet
I wouldnt think Fan would kick into high untill 218ECT when the thermistate is fulley open
does your coolant temp sensor read Erratic
sometimes my TFT sensor will read erratic as it warms up
fan clutch harness ok fulley plugged in an no wire chaff at the connector not corroded inside
just thinking out loud
you wont have to worrey about overheat anyway
does it do it on the HWY too