Codes 0035, 0036, 0037 and P0502

VICKY RICHARDSON

MEMBER
1996 CHEVROLET TAHOE
5.7L
V8
4WD
AUTOMATIC
141,000 MILES

I had new tires put on the vehicle and when I drove it the ABS light came on. Immediately after the service engine light came on. The vehicle then felt as if I put it in neutral and was accelerating then it would jerk into gear. A scanner shop I was sent to by Discount Tire said the sensors were tested and were fine. I asked him for the codes and I was told 0035, 0036, 0037, and p0502.
Unfortunately I didn't have the financial means to have anyone diagnose the actual problem so it sat. I did some research and figured I would have to start somewhere so I bought a speed sensor from Amazon and had a new neighbor replace it. When I test drove it it felt okay at first until I accelerated quickly while making a left turn. It didn't feel like it jerked into gear it felt more like a jumping feeling. I know there are 4 wheel speed sensors. I have located the 2 on the front. Well actually the harnesses. The rear ones I haven’t really looked bit didn't see anything obvious like the front. If you would please advise me of the proper steps I should be taking to get this problem fixed. I will go get photos now to send. Thanks so very much

1 Reply

STEVE W.

MECHANIC
13,465 POSTS

Welcome to 2CarPros. The codes you were given are interesting.

P0035 - Turbocharger Bypass Valve Control Circuit High
This one you can ignore, Your truck isn't turbo or supercharged, unless you actually have the 6.5 Diesel engine and not the 5.7 gas.

P0036 - Heated Oxygen Sensor Control Circuit B1S2
P0037 - Heated Oxygen Sensor Control Circuit Low B1S2
A common cause for both of these codes is a bad O2 sensor or the wiring to the sensor is damaged. Because both codes relate to the same rear O2 sensor it is possible that the wiring harness was loose and got pinched on the lift or it was caught and pulled off. This should be easy to find if you look at the wiring that comes off of the rear O2 sensors. Look for pinched or broken wires in a damaged harness

P0502 - Vehicle Speed Sensor A Low Input
This is going to be the sensor on the transmission (sensor A), not the wheel speed sensors.
This code could be set by a few things, however if changing the sensor didn't fix it I would bet it has damaged wiring as well. Especially as the speed sensor harness runs near the O2 sensor wiring underneath.

Another item to check on this vintage truck is the ground strap on the back of the cylinder head that provides the ground from the engine to the body. They corrode off and can cause odd behavior as the current tries to find a return path.