I just found this site, and hope I can get some answers to some problems I have with my 97'Tahoe, 4w/d
#1 The dreaded ABS brakes. At around 80,000 miles I experienced a pulsing of the brakes when slowing down and almost stopped. To make a long story short, I took it to the dealer who said both front hubs needed replacing because the bearings were bad. $$$$$ later, they corrected the problem. Now the truck has 120,000 miles on it and the problem is back again. This time the pulsing only happens now and then. I believe the problem is in the sensor(s) and not the bearings. Does anybody know how I can check the sensors for calibration, and if replacement sensors are available? Their nothing more than a magnet!
I read somewhere you can ohm them out, but I found different readings which contradicted each other, so I don't know which if either is right.
#2 The truck wanders quite a lot. At one time I had an experience where the steering seemed to lock up for a second, then free back up. I don't seem to get the lock up anymore, but it seems as if I'm always having trouble keeping the truck straight. The suspension seems tight, and the idler arm was replaced a while ago. There is almost zero play in the steering wheel, when the engine is off. I'm due for tires this fall, so I'm not doing anything major until their installed, to see if that corrects the problem. I read on other forums that there is an EVO sensor on the steering column that can cause this. Could this be my problem? This sensor seems to have a variety of names. What is on my 97'?
#3 When I have the overide button for the interior lights pushed in, (no interior lights) I get a clicking sound from under the dash, near the button, while driving, and the interior lights flash. Is there a short in the button, or what? It only clicks when in overide. If the button is bad, is it easy to replace?
#4 I often listen to AM stations on the radio, but find that unless the station signal is very strong, I'll get a whistling sound every time I step on the brakes. It will go from a low tone to high pitch and back again. I assume it's electronic interference from the brake computer, but does anyone know how to prevent it?
#5 Does anybody know of a web site where I can look up the information contained in technical service bulletins, beyond just the number and date it was issued. There must be something out there that's FREE!
Sorry for such a long post, but I sure could use some answers to these ongoing problems. Thank's in advance for any and all responses.
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This should take care of item #1:
Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph)no DTCs set.
The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.
Measure AC voltage and clean wheel speed sensor mounting surfaces.
Raise the vehicle on a hoist.
Disconnect both the front wheel speed sensor harness connectors.
Place a DVM across the terminals of each sensor connector.
Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's.
If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor.
Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service.
Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, ScotchBrite™, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (Canadian P/N 89022218).
When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037).
Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub.
Install the rotor, the caliper and the wheel.
Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's.
Try this to fix Item #2 with the exeption that if at times the steering seams to lock then just go ahead and replace the steering spool along with these other items:
STEERING WANDER OR THE PERCEPTION OF LOOSE STEERING AT HIGHWAY SPEEDS
CHECK. PERFORM THE FRONT WHEEL ALIGNMENT PRELIMINARY INSPECTIONS. VERIFY THAT THE FRONT SUSPENSION "Z" DIMENSION IS WITHIN SPECIFICATIONS PER THE TRIM HEIGHT CHART.
DISCONNECT THE LEFT AND RIGHT TIE ROD ENDS AND CHECK FOR TIGHT OR BINDING BALL JOINTS AND THAT THEY ARE PROPERLY LUBRICATED. IF ALL COMPONENTS AND SPECIFICATIONS ARE CORRECT, ADJUST THE FRONT WHEEL ALIGNMENT TO THE FOLLOWING SPECIFICATIONS.
CASTER 3.80 TO 3.90 DEGREES
CAMBER 0.5 DEGREES 0.5 DEGREES
SUM TOE-IN .24 DEGREES 0.2 DEGREES
IF CONDITION PERSISTS, - ON VEHICLES BELOW 8050# GVW, ADJUST THE STEERING GEAR SPOOL VALVE PRELOAD AND SECTOR PRELOAD FOLLOWING THE PROCEDURE DESCRIBED IN SECTION 3B1A. - ON SUBURBANS EQUIPPED WITH 6.5L DIESEL ENGINE, UNDER 8600# GVW, BUILT PRIOR TO MARCH 5, 1997, REPLACE THE STEERING GEAR WITH P/N 26068771 AND THE EVO MODULE, P/N 16259515. - ON VEHICLES ABOVE 8500# GVW, REPLACE ONLY THE STEERING GEAR WITH P/N 26068771.
I assume from your response to my 1st question that replacement wheel sensors are available. Are they only available from the dealer or can I get them aftermarket? Any chance you have a part number, and do both sides take the same sensor, or are they different? As far as the corrosion inhibitor is concerned, it sounds like another dealer item, correct?
I appreciate the time taken to assist me. This is the first positive information I've obtained. Up to now, I've been flying by the seat of my pants.
As far as item #2, I'll have to do some checking to decipher the language wording. But thank's anyhow.
Dealer only parts
As far as part # I don't have them and don't work with GM parts but your local dealer can assist just be sure to have VIN info, the parts are not that expensive and be sure to ask for a discount.
I just did some copy and pasting. The language in item #2 sounds complicated but basically in a nutshell it means to just have the front end aligned to those specifications, any reputable shop will complete the aforementioned preliminary inspection before attempting a re-alignment.
Thank's again for your help. Let me clairfy the problem with the steering. Maybe wander is too vague. While driving, if I wiggle the steering wheel back and forth slightly, I can feel the front end wobble right with the movement. The response seems there, it's just that the steering feels very loose. Even at highway speed, the steering doesn't seem tight. I think Chevy calls it variable effort steering. With this in mind, should I still follow thru with your recomendations on having the alignment checked?
I had a steering problem on both my 1998 Chevy pickup and my 1998 Suburban. The best I can describe it is that sometimes it felt as if I were driving on ice. On both trucks, I replaced the steering sensor. It's a donut looking piece located at the bottom of the steering column. Problem solved on both trucks.
I just found this site and have a 1995 Tahoe with 255,000 miles on it and I'm having trouble keeping it on the road with loose steering. In a strong wind or rough road it feels like driving a boat, the front end seems to drift. I have had the front end aligned (twice) and replaced the shocks. I did put cheep tires on a few months back that I think may be adding to the issue but with the car running there is 2-3 inches of play in the wheel before the tires move???