LS6427

iTrader: (2)

Sick of searching and not finding anything.


Who knows what the coolant temp needs to be at for the fans to stay "on" after the engine is shut down and the key is removed?

What does it mean when the A/C is "off"........the fans DO NOT continue to run with the engine "off" , key turned forward to the "on" position....but if you start it the fans come on.....

Also, how many fan relays are there? Just the ones in the under hood fuse boxes?

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wrencher

iTrader: (2)

3 relays in underhood box. The fans shouldn't run after key off IIRC.

LS6427

iTrader: (2)

I think my t-stat is stuck than.......I ran really hot yesterday for the first time ever. Just 10 miles, 7 of which were highway. Strange.

I thought if temps were too high, the fans kept running.

I'll check t-stat tomorrow. Thanks.

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wrencher

iTrader: (2)

Might have another issue also the PCM turns the relays on to activate the fans.
It uses 3 relays to have a low & high speed operation.

LS6427

iTrader: (2)

The relays are all cheap, right? Maybe I'll just replace them all, they're 13 1/2 years old.... lol


The fans were both running on HIGH when I got to my friends house....engine idling.......but the temps were jacked up higher than I've ever seen them. Especially highway cruising.


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wrencher

iTrader: (2)

Well get the cooling system in order than if the fan where working overtime & the gauge was up has to be a problem.
The relays are not bad you can prolly get delco replacements for 20 max a piece....
Never really trust a coolant gauge on the 99's & up to be spot on accurate.
Dont overlook the coolant temp sensor also as an issue IF all else checks out well.

2001NBMZ28

According to my helms the fans will stay on for approximately 3 minutes after key off if the PCM sees 284*.

1SLwLS1

iTrader: (6)

The PCM commands low speed fans on under the following conditions:

Engine coolant temperature exceeds approximately 108°C (226°F).
When A/C is requested and the ambient temperature is greater than 10°C (50°F).
A/C refrigerant pressure exceeds 1482 kPa (215 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 113°C (235°F) and system voltage is more than 12 volts. The fans will stay on for approximately 150 seconds.


The PCM commands High Speed Fans on under the following conditions:

Engine coolant temperature reaches 112°C (234°F).
A/C refrigerant pressure exceeds 1710 kPa (248 psi).
When certain DTCs set.

2001NBMZ28

That's exactly the same I was reading on page 6-826 in my helms, except it says 284*F key-off. Maybe a typeo or a little different from year to year?

jam01

there is a write up here about the power steering cooler leaking, maybe that would help. j/k you could try running a manual switch to the fans, ive done that on my street strip cars, if i remember you still use the relays the switch just bypasses it.

was it overheating while driving or sitting idle in traffic?

LS6427

iTrader: (2)

Thanks for the info...........I'll check it all. I guess if my fans stayed off after I took the key out...it was less than 235*F.

I'm gonna do a flush and check the t-stat.

I know our gauges are not accurate and should just be used as a guide day-to-day....but it was showing 60 degrees higher than usual.......and when i popped the hood, things were friggin hot. I can always keep my hand on the intake no problem......not this time.

LS6427

iTrader: (2)

I drove about 2 miles to a highway, got on and did 75mph for about 7 miles, then 1 mile to my friends house. Usually it gets up to about 180*F (on the gauge), this time it was at the 240*F mark. My temp gauge NEVER in 13 1/2 years has even gotten close to even the 225*F mark.

Normally, my temp gauge would be about 60*F less than that for that trip, which I do 3-4 times a week. Something is wrong.......when I popped the hood, the engine bay was VERY hot. I know my car very well and it was really hot....for real.

Hope the t-stat is just going bad............because the fans were cranking on HIGH when I popped the hood at my friends house, while the engine was idling.

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1SLwLS1

iTrader: (6)

284*F seems a bit high, but I am not positive.

jam01

yeah if your driving at highway speeds it is an obstruction somewhere either in the cooling system or in front of your radiator. pull the stat out and run it, if it runs cooler there you go. dont forget to look for a plastic bag or something while your there.

LS6427

iTrader: (2)

I just went for a drive. Before I did I checked for anything stuck up in front of the condensor.

It got hot just driving 3 miles to the bank and then about 3 miles over to Advance Auto. When I got out at Advance Auto the needle was just under my 215*F mark on the temp gauge....but the engine bay was HOT.....

Fans were both running on HIGH. When I turned the engine off the fans stopped. So I guess I was under 235*F.

Gonna flush it tonight and check the t-stat in a pot of water.......coolant is really clean though....so it might be the t-stat sticking partially opened.

Thanks.


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jam01

i hope i pointed you in the right direction, also make sure you have coolant flow, pull the cap off the rad and let it run until its warm. you should see some movement in there. make sure the pump is ok, its hard to diagnose over a computer.

LS6427

iTrader: (2)

Yea...I couldn't do a damn thing today, stuff came up for work. Had to plan a 5-day trip leaving Thursday.

Gonna try to mess with it tomorrow.

I'll start with a flush cause its due anyway. I always take the t-stat out for the flush so coolant continually flows so it doesn't take so long waiting for the t-stat to keep opening and closing. I'll check the t-stat while its out.

If the pump wasn't working I wouldn't last 10 minutes of driving, needle would be in the red fast. Coolant is topped off and doesn't leak a drop. Its a strange one, since I've never had any kind of overheating issue in 13+ years down here in this hot *** place.

I'm thinking sticking t-stat. Its 9+ years old.

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