Last post on Oct 12, 2006 at 5:32 AM
You are in the Chevrolet Silverado & GMC Sierra
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GMC Sierra 1500, GMC Sierra 2500, GMC Sierra 3500, Truck
#1320 of 1492 Re: Electronic Variable Orifice-What is it? [noobie1]
Feb 04, 2006 (11:47 am)
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]
Feb 04, 2006 (4:26 pm)
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]
Feb 05, 2006 (8:20 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':
and this at: http://findarticles.com/p/articles/mi_qa3707/is_200504/ai_n13499665
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.
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.
#1323 of 1492 Speedometer stuck on 100 MPH
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?
#1326 of 1492 Re: 03 hd fuel filter problem [12run4]
Feb 14, 2006 (10:54 am)
I purchased my 03 GMC Sierra 3500 mid December 2005 with 118,000 miles. It now has a little over 119,000 miles and now I have been told all injectors and the pump must be replaced. I was not being able to get it to start. One time it would, next time could not do anything to get it started. Do you have any reference I can go to regarding the extended warranty to approx. 180,000 miles. Dealership has told me this would be covered under warranty but now they are saying it will not and they can't get the GMC rep to do anything about it. Any help would be MOST appreciated.
#1327 of 1492 96 GMC Suburban ABS Light
Feb 14, 2006 (11:22 am)
My light has been on for awhile, I have has oversized 35" tires on my truck for years. Just recently, the light came on and stay on. The scanner was put on and it said that BOTH front wheel sensors were bad, after resetting in park and engine off, the right one kicked the light on immediately. Does anybody have any ideas on how to repair? I have been getting 2 stories about the sensors that they clip into the hub and the other that they are attached to the wheel hub and must be purchased as a whole unit. Help me out guys!!!!
#1328 of 1492 Bad Brake Vibration @ 7,000 miles?????!
Feb 16, 2006 (6:25 pm)
I have a 2004 GMC Sierra 4x4 with only 7,000 miles on it. Just after 6,000 miles, it began to show a really bad vibration/shudder when the brakes are applied. I brought it to the dealer who of course could find nothing wrong (typical excuse). Now when I lightly apply the brakes, the truck begins to shudder and it seems like 30 mph and under is the worst. It begins to shake and it gets so bad that that I can actually hear a knocking sound! It is an awful sound. I am not 100% sure that it could be warped rotors......and I would almost think it could be ABS, but no lights come on. The truck did sit in a garage for some time, like 5-6 months and there was some rust build up on the rotors that has since worn away and they are shiny. Can anyone offer some help on this, it must be fixed!
#1329 of 1492 Re: Bad Brake Vibration @ 7,000 miles?????! [dale3n8]
Feb 16, 2006 (6:51 pm)
Do you wash your truck at car washes and apply liquid wax? Or use products like ZipCar wash in a bucket of water and handwash the truck? If wax gets on the brake rotors, it will contaminate the pads and possibly cause horrible griding and screeching noise when brakes are lightly applied. I had something like this happen with a passenger car. The solution was cleaning the rotors with acetone, and lightly sanding them by hand with 100 grit sandpaper to remove the glaze. Also, I replaced the brake pads and made sure that the caliper sliding pins were lubricated and sliding freely. This solved the problem for good.
Rotors can get warped by uneven lug nut tightening with an air impact gun (unless they use a torque extension with it). Did you have your tires rotated and did they use an air gun on your lug nuts to tighten them? However, warped rotors usually cause pulsation it the brake pedal and chatter when braking hard at high speeds. Brake chatter at low speeds under light braking conditions can also be caused by sticking cliper sliding pins.