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I tow a fairly heavy trailer with my '04 trailblazer ext. I had an overheating issue and I had a dealer replace the factory cooling fan with 2 electric fans. Works fine, but here is the issue. My SES light has been on since I had this done and I check every 2 weeks for other codes. I now need to pass a emissions test to get my vehicle inspected in PA. The state will not do a tailpipe test on the vehicle and the SES light will no let it pass the emission test. Is there a 'JUMPER" I can create to fool the computer into thinking that the factory fan is still there? My fuel milage actually increased after having the electric fans installed and the overheating is a non-issue now.
Any Ideas?

Hello dudley_rich, You cannot

Submitted by Helene Car Lady on Tue, 11/29/2011 - 10:13.

Hello dudley_rich,

You cannot bypass or trick the PCM. To resolve the issue the are describing you must apply the TSB shown below. You can get the TSB from a dealer. In the month of October I had 19 cases where PO526 was set in 2004 Trailblazer vehicles. I used the posted TSB to resolve all 19 cases.

Thank You
Helene

TSB #05-06-02-012B.

With all due respect. I

Submitted by dudley_rich on Wed, 11/30/2011 - 03:08.

With all due respect. I cannot replace the wiring harness, as suggested in the TSB. The issue is that the factory fan is completely gone, so there is nothing to fix. I had an overheating problem that was remedied by replacing the factory belt driven clutch fan with dual electric fans. So, the wiring harness is not the issue.
I was able to contact PCMFORLESS.COm to bypass the P0526 engine code and that worked just fine. It was also about 1/4 of the cost.
Thank you for your suggestion.

Dudley, Out of sight out of

Submitted by Big Block 409 on Wed, 11/30/2011 - 04:37.

Dudley,

Out of sight out of mind doesn't mean you fixed the problem. The problem is still there and it's gonna stay there until you apply the TSB. You do what you gotta do to fix the problem, even if that means replacin the harness and puttin back any OE parts that were removed. Look at it this way.

If you put a bucket on the floor to catch the water caused by a leaking roof, have you REALLY fixed the roof?

How do I fix something I

Submitted by dudley_rich on Wed, 11/30/2011 - 07:09.

How do I fix something I threw away 4 years ago? I was overheating when I towed with the factory fan, so I replaced it with an effective cooling system. So applying the TSB to something that doesn't exist is futility.
My current electric fans are straight wired to the fuse block and run constantly, which keep my engine cool at all times.

Dudley, Haven't forgot about

Submitted by Big Block 409 on Thu, 12/01/2011 - 05:22.

Dudley,

Haven't forgot about you buddy. Just been really busy lately. Got an answer (and more) for you regarding your below statement. Just keep checkin back on the forum from time to time for my answer.

(You said) How do I fix something I threw away 4 years ago? I was overheating when I towed with the factory fan, so I replaced it with an effective cooling system.

Big, That was my ORIGINAL

Submitted by dudley_rich on Thu, 12/01/2011 - 09:28.

Big,

That was my ORIGINAL question. When I COMPLETELY removed the stock factory fan, my SES lite came on. I use a code reader roughly every 2 weeks and the only code I get is the P0526 code telling me that the fan is not up to speed. Duh? When I have to get a PA emissions inspection, they just do an OBD test to check for codes. With the SES light on, it would not pass the test. I have, since the SES light came on for the P0526 code, caught a bad rear O2 sensor code and fixed that.
Well, long story short, even though the factory fan was completely gone, I could not clear the code for very long. That is the reason I had the PCM coded to bypass the P0526 error, since it wasn't really applicable.

Dudley, This is gonna be a

Submitted by Big Block 409 on Fri, 12/02/2011 - 05:31.

Dudley,

This is gonna be a long answer man and it’s gonna be in stages. Just keep checkin back for more info from time to time. By late this afternoon (early evening) all that needs to be said will have been said. It’s gotta be long and it’s gotta be in stages, because you’re the victim here man, and that’s because the dealer screwed you over. The dealer is responsible for the setting of PO526, and now you’re left holdin the bag. Just keep readin and keep checkin in, and you’ll finally see what I’m talkin about.

For future reference dealers are good for ONLY three things.

Recalls, since they are free.
Moving your bowels.
And urinating.

The last two are because the bathrooms in dealerships are always clean and never out of toilet paper. Furthermore since I'm on the topic of bowel movements, and since this is a friendly and family forum I’ll pass on what I have to say about service managers and dealership auto mechanics.

(You said) I had an overheating issue and I had a dealer replace the factory cooling fan with 2 electric fans.

Your above statement is where your problems began.

First some background.

The setting of P0526 means there is a fault within the fan speed sensor circuit. Simply stated the PCM uses a speed signal from the cooling fan to determine the actual fan speed in comparison to the original OE recommended threshold (or fan speed). Without getting into too much technical detail here, the PCM will set DTC P0526 if it detects a loss of cooling fan speed for more than 11 seconds and will set the MIL after the second consecutive incident of diagnostic testing has been run yielding the same failure/error.

Common issues associated with the setting of PO526.

Loose or damaged wiring
Chaffing in the electrical fan harness
A faulty fan clutch
A faulty speed sensor

The speed sensor is situated inside the fan clutch, which has an electrical harness connected to it. The first move is to check the wiring to and from the harness, the fan clutch etc. If the wiring is undamaged, the fault may lie within the harness, where chaffing is a common problem. The harness may be replaced by removing the cooling fan, disconnecting the harness from the fan clutch and removing the harness from its plastic guide while feeding the wires out through their slot. The new harness is then installed in reverse order. If the clutch itself is the problem, it can be replaced by disconnecting the negative battery lead, draining the coolant, removing the top radiator hose and the fan shroud. This is followed by loosening the fan bolts on the fan clutch. The main fan clutch bolt will have to be removed using a fan clutch tool, which can be rented. At this point the electrical harness can be disconnected. The process is done in cess is reverse to install the new clutch.

Don, I'm about to end this

Submitted by Big Block 409 on Fri, 12/02/2011 - 15:02.

Don,

I'm about to end this thing and tell you:

What happened
How the dealer dropped the ball
How the dealer screwed you and set PO526
What you need to do to resolve PO526 once and for all?
Never have another problem with overheating again

Bump
Bump
Bump

Are you out there?