Ed, The reason the sensor went bad is due to that lower steering column bearing has failed. I found a thread which explained this so I went to my truck and sure enough the bearing wobbled all over the place. check that bearing.The problem: The steering on the vehicles that utilize this part slowly gets less responsive, feeling a little like a worn rag joint and a little like the steering box is in need of a fine tuning, or worse replacement. It starts a little at a time and worsens to the point where it feels as if, while making a turn, your front wheels have both slipped sideways -as if you have just hit a small patch of black ice.The front end suddenly sideslips; but not to the point where you lose any real control. It is more like feeling a very strong crosswind on the freeway.
You will also start to feel as though your steering linkage has become loose- you get the feeling as though the pitman arm that controls the rest of the steering linkage has a couple inches of slop in it that only shows up when coming off of a direct straight-ahead course. Most turns of the wheel- noticably between the 11 'oclock and 1 'oclock position, become from clicky at first to clunky, if not fixed.
The details: The problem is all to often a part on the steering shaft that is known as the "steering Speed Sensor"It is mostly a dealer chevy part and even www.gmpartsclub.com and their ilk may run 60-75 bucks. The discounters usually make up on the low price with absorbatent shipping. The GM part number is 26064468. Many references to this part are made as "the EVO" You'll get further faster with the parts guy by saying "steering Speed Sensor". AFter searching and finding it at 1A auto.com for 27.95. I lit up only to see that they were out of stock. More searching turned up a replacement at NAPA Auto Parts p/n BK 620-2250- go pick one up for 35.99- can you stand it?
Installation: Tools: get a small bright flash light, a medium length "prying thickness screwdriver, household weight hammer- not too big-no room, a shop towel, a medium length 15mm socket/ratchet wrench. Comfy clothes that you can move upsidedown in.
The removal/replacement. Time 20-30 minutes. Near the bottom quarter of the steering shaft- under the dashboard, you'll find a cast metal collar that belongs to the steering shaft that passes through the firewall and connects to the steering column in the vehicle. A plastic ring circles the shaft above it. This is where you'll be working. Before disconnecting the neg battery terminal at the battery, watch the shaft from under the dash. With the key in place to unlock the steering- you may have to start the car, turn the steering wheel until the nut on the steering shaft can be easily accessed with a socket wrench. Turn the wheel back and forth to relax the wheel in this position, then remove the key from the column- locking the wheel in this position. Now disconnect the neg battery lug from the battery.
Remove the nut from the shaft- Don't confuse this nut/bolt with the two bolts holding the steering column to the frame. Use the hammer and screwdriver to tap the bolt upwards and free of the column.
The lower shaft must now be pulled a few inched back about 4-5, to allow removal of the old sensor. Use the hammer handle to slowly massage the cast collar back towards the hole in the firewall on the lower end of the shaft. It will take some effort; but work slow so as not to break the collar with the hammer. This seems like it would be easier in warm weather; it was cold where I live. Once the collar is completely free of the upper shaft spline you can remove the old sensor.
The chevy sensor is held inside of the visible plastic ring by 3 tabs- the kind that always break when you try to pull a connector out on a wiring job. The tabs are evenly spaced around the ring. There are slits next to each tab that you can put a very tiny screw driver in to dig the sensor out as the tabs are held back. I used some sharp point exacto blades as wedges and the sensor popped out as each of the tabs were pulled back. Once the sensor is free you need to disconnect the connector of the sensor's pigtail. It is a single connector with three wires. Note the routing of the wire and the look of the sensor's side that faces up toward the steering wheel. Slip the sensor off of the shaft. Use the screwdriver to pry the cast collar aside to make room for the sensor to come off, and again for the new sensor to be slipped on the shaft.
Connect the new sensor to the wiring connector before threading the sensor over the shaft. When the new sensor is on the shaft rock it gently upwards until it slides into place. The base of the new sensor's pigtail slips into a notch on the housing. Once aligned, the sensor can be seated past the 3 locking tabs. It is important to seat the sensor into the housing completely without damaging the center bearing assembly.
Button it up. The collar on the lower steering shaft must now be brought back in to slide up onto the shaft. This is the hard part- but only moderately so. By unlocking the steering wheel again and turning the shaft to match the collar assembly, a little massaging will get the collar on the shaft enough for you to start tapping the collar upward with the hammer. Do this until you see the bolt holes realign. Slip the bolt in from above. Start and tighen the nut to about 44 lbs. There is a rubber collar over the lower steering shaft on the engine side of the firewall. It seems to reseat itself; but check that it is in place.
This is one of the few elctronic parts that have truly felt as if there was a breakdown of the mechanical parts. Complete with clunking and bumping. You will save a lot by doing this yourself, before you have it diagnosed as a big, and possibly unnecessary repair. Good luck.
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