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GMC Sierra: Problems & Solutions - READ ONLY

1492 messages,  Last post on Oct 12, 2006 at 5:32 AM

You are in the Chevrolet Silverado & GMC Sierra Forum. Your Host is kcram

What is this discussion about? GMC Sierra 1500, GMC Sierra 2500, GMC Sierra 3500, Truck


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#1316 of 1492
Re: Heater Problem 2001 GMC [aebert] by denton1
Jan 31, 2006 (8:27 pm)

Replying to: aebert (Sep 16, 2001 6:11 am)

Did you find a answer to this problem
#1317 of 1492
Electronic Variable Orifice-What is it? by mikec8
Feb 03, 2006 (3:38 pm)
It's been suggested that the problem I'm having with my steering wanting to jump an extra amount when I am going around a right curve might be caused by the EVO going bad. Anyone know if that's possible or what else might be causing it. I've posted before on this problem. It's a 97 K-1500. Dealer can't find it and wants to experiment, probably at my expense. I e-mailed GMC corp customer service but that didn't help either. Apparently it's a part of the steering system. Thanks....Mike
#1319 of 1492
Re: Electronic Variable Orifice-What is it? [mikec8] by noobie1
Feb 03, 2006 (4:55 pm)

Replying to: mikec8 (Feb 03, 2006 3:38 pm)

Mike; When you mentioned this before I looked in my manual and about all I could find then was the definition of EVO. I'll search again and try and get back to you this week-end.
 
-David
#1320 of 1492
Re: Electronic Variable Orifice-What is it? [noobie1] by mikec8
Feb 04, 2006 (11:47 am)

Replying to: noobie1 (Feb 03, 2006 4:55 pm)

Thanks David. I appreciate the help. The steering issue is getting more frequent, sometimes "jumping" a couple of times in one curve on the highway. It is interesting that it only does it when turning the wheels to the right....Mike
#1321 of 1492
Re: Steering Problem-'97 K1500 Sierra [gmc2004crew] by mikec8
Feb 04, 2006 (4:26 pm)

Replying to: gmc2004crew (Dec 07, 2005 10:40 am)

Regarding the 97 1500 steering problem. You mentioned awhile back that you had the EVO sensor replaced. Do you recall the cost. I'm willing to try it, I think. My dealer's garage tends to experiment without exhibiting much real knowledge or confidence. If too much, I might try to do it myself. Thanks....Mike
#1322 of 1492
Re: Electronic Variable Orifice-What is it? [mikec8] by noobie1
Feb 05, 2006 (8:20 am)

Replying to: mikec8 (Feb 04, 2006 11:47 am)

Mike; Couldn't find much help in the service manual. But, here's a couple of links I found by Googling 'Electronic Variable Orifice' and 'EVO sensor':
 
http://www.delphi.com/pdf/ppd/chsteer/str_evo.pdf
 
http://www.asashop.org/autoinc/april2005/techtips.cfm
 
and this at: http://findarticles.com/p/articles/mi_qa3707/is_200504/ai_n13499665
 
   "Steering Shake
 
IHAVE A 1998 GMC SUBURBAN 1500 4WD with the 5.7-liter engine. I recently put a new set of Goodyear Fortera HL tires on. This is when I noticed a shake in the steering wheel between 30 and 40 MPH. It doesn't happen all the time, but it can occur at any time and at any speed between 30 and 40 MPH.
 
A mechanic and I ruled out the cause being a bad tire by swapping tires around, using known good tires and wheels. The mechanic subscribes to an online database/chat room for mechanics. After researching this site and asking questions, he narrowed the problem down to two likely causes, the EVO sensor (which I believe goes around the steering column under the dash) and an actuator valve at the power-steering pump that regulates pressure for the speed-sensitive steering. Neither of these corrected the problem. However, when the connector at the pump actuator is disconnected, the problem is gone.
 
RANDALL COWAN
 
Middle River, Maryland
 
The steering-position sensor is used to tell the computer the position of the steering wheel and how fast the driver is turning the wheel. Based on that information and also on vehicle speed, it will vary the steering effort by controlling the bypass orifice to relieve powersteering-pump pressure. There are two likely conditions that will cause the system to malfunction - a lifted suspension or oversized tires with extreme rim offsets. Both of these will change the force to the steering gear and cause a hydraulic oscillation. In layman's terms, the steering wheel will shake.
 
The easiest way to diagnose the problem is to apply the brakes on dry pavement and turn the wheel lock to lock (while the vehicle is stationary). If it takes some strong-arm work to move the steering wheel, then the pump pressure is not high enough. Correct that first and then look at some type of tuned hose that acts as an accumulator to dampen the hydraulic oscillation. A spiral-wound spring inside the pressure hose will help dampen the fluctuation of pressure. You should be able to find a local custom-hose builder to do it. You could also temporarily install stock-type and stock-size tires up front and drive the truck to see if the problem goes away, which would further help you isolate the source of your shaking. - K.F."
 
You might, just as an experiment as suggested in the above, disconnect the electrical connector at the actuator (rear of the pump) to see if that eliminates the problem . If it does, you won't know if it's the actuator or the EVO sensor, but at least it puts you in the ballpark. Let us know how it turns out.
 
-David
#1323 of 1492
Speedometer stuck on 100 MPH by chelfish
Feb 11, 2006 (7:45 am)
My battery went down (due to lack of driving)on my 96 GMC Sierra 1500 so hooked up the battery charger. When I did the Code Alarm activated and the speedometer needle bounced around. Once I shut the alarm off the speedometer is stuck on 100 MHP. Any ideas?
#1324 of 1492
Re: Electronic Variable Orifice-What is it? [noobie1] by jaytexas
Feb 11, 2006 (10:24 am)

Replying to: noobie1 (Feb 05, 2006 8:20 am)

take a look at this site for some good background on EVO
http://forums.vmag.com/suvtahyuk0301/messages/5078.html
#1325 of 1492
Chevy EVO Sensor Replacement, Repairs Loose Steering Feel by jaytexas
Feb 11, 2006 (11:06 am)
http://www.automotiveforums.com/t317059.html

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