97 gmc sierra erratic steering

[blue97gmc]

My 97 GMC sierra k1500s steering "jumps" when turning. I've read posts about the "evo sensor" and even bought one to have installed only to find that my truck does not have that option. The mechanic told me there was just a steel plate where the sensor goes. He checked the vin and options and mine does not have one. Any other suggestions?

[kstruckcountry]

Are you talking about higher speed prolonged turns?

[blue97gmc]

No. Almost any speed 30 or greater. Just slight turning, trying to stay in my lane. Like I hit a lip in the road.

[1997SierraSLT]

about 10-12 years ago there were thousands of complaints and numerous vehicle crashes on NHTSA's website pertaining to this erratic steering issue. 1997 was the first year VSS (variable speed steering) was introduced into GM's product line. There is a sensor that is mounted to the steering column under the dash. It's a rotary type potentiometer. It is tied into the ECM and also a solenoid that is mounted inside the power steering pump. At slow speeds, this allows for fingertip steering capabilities. As you increase speed, it becomes harder to steer as the steering wheel is turned (increased resistance). This is accomplished by the solenoid in the power steering pump. The solenoid either increases or decreases line pressure to the steering gearbox depending on vehicle speed and rotation of the steering wheel.

 

NHTSA conducted an investigation and cleared GM of any design flaws. I'm going to assume NHTSA was paid off handsomely since GM incoporated this VSS feature into millions upon millions of vehicles. GM never issued a recall or technical bulletin to fix this problem. But you know how it is......if nobody gets killed because of it, the problem is ignored and if someone sues, a corporation simply settles out of court to make the problem go away.

 

I'm quite familiar with this problem. It is most prevalent on nice sweeping turns at around 40 mph. The steering wheel violently jerks out of your hand. What's happening is ECM is experiencing a glitch. The potentiometer provides a false reading and sends a signal to the ECM which sends a signal to the solenoid in the power steering pump to provide full power assist (increase in line pressure). I've replaced this VSS sensor about 4 times since I've owned my 1997 GMC K1500 with 155,000 miles on it thinking that was the problem. The VSS does not appear to be the "complete" problem as again, it's a simple potentiometer. I've taken them apart and there is nothing to them. This leads me to believe there is a glitch in the ECM.

 

So what I've done is remove the VSS from the steering column and taped it into a TDC position to keep it from rotating. I'm in essence tricking the ECM. The downside to this is that steering can be a little lighter than I'd like at highway speeds. But, the ECM also takes into account road speed and adjusts the solenoid accordingly. It's not like I have full power assist going down the road at 70 mph. If you decide to disconnect the wiring harness from the solenoid or the VSS, you'll have full power assist at any road speed and it is very dangerous.

 

Even with my modication in place, I will experience the VSS glitch, but the frequency at which I experience it is very low. Hope this helps.

[blue97gmc]

scw1991: thank you for your reply. I'm getting the VSS sensor replaced on Monday. I guess I'll start there. Your reply was very helpful, thank you again for your time.

[2018GMC]

about 10-12 years ago there were thousands of complaints and numerous vehicle crashes on NHTSA's website pertaining to this erratic steering issue. 1997 was the first year VSS (variable speed steering) was introduced into GM's product line. There is a sensor that is mounted to the steering column under the dash. It's a rotary type potentiometer. It is tied into the ECM and also a solenoid that is mounted inside the power steering pump. At slow speeds, this allows for fingertip steering capabilities. As you increase speed, it becomes harder to steer as the steering wheel is turned (increased resistance). This is accomplished by the solenoid in the power steering pump. The solenoid either increases or decreases line pressure to the steering gearbox depending on vehicle speed and rotation of the steering wheel.

 

NHTSA conducted an investigation and cleared GM of any design flaws. I'm going to assume NHTSA was paid off handsomely since GM incoporated this VSS feature into millions upon millions of vehicles. GM never issued a recall or technical bulletin to fix this problem. But you know how it is......if nobody gets killed because of it, the problem is ignored and if someone sues, a corporation simply settles out of court to make the problem go away.

 

I'm quite familiar with this problem. It is most prevalent on nice sweeping turns at around 40 mph. The steering wheel violently jerks out of your hand. What's happening is ECM is experiencing a glitch. The potentiometer provides a false reading and sends a signal to the ECM which sends a signal to the solenoid in the power steering pump to provide full power assist (increase in line pressure). I've replaced this VSS sensor about 4 times since I've owned my 1997 GMC K1500 with 155,000 miles on it thinking that was the problem. The VSS does not appear to be the "complete" problem as again, it's a simple potentiometer. I've taken them apart and there is nothing to them. This leads me to believe there is a glitch in the ECM.

 

So what I've done is remove the VSS from the steering column and taped it into a TDC position to keep it from rotating. I'm in essence tricking the ECM. The downside to this is that steering can be a little lighter than I'd like at highway speeds. But, the ECM also takes into account road speed and adjusts the solenoid accordingly. It's not like I have full power assist going down the road at 70 mph. If you decide to disconnect the wiring harness from the solenoid or the VSS, you'll have full power assist at any road speed and it is very dangerous.

 

Even with my modication in place, I will experience the VSS glitch, but the frequency at which I experience it is very low. Hope this helps.

 

Thanks for the detailed post. My 1997 K1500 exhibits this problem occasionally. Always seems to happen in a long turn when all the sudden there is a jerk in the steering which usually causes me to say an expletive and continue on my way.