1999 Chevy Tahoe Lt
Engine size = 350
ABS and Check engine light
codes = P0502
tech = mw
question = I was driving and the ABS light came on. When I applied the brakes the started
grinding. Afterwards the transmission started slipping and wouldn't shift higher than third at
3000 rpm's. Does the speed sensor control the shift rate of the tranny and if so how do I
replace it.
MW:
Hello and welcome. Sounds like you have multiple problems here. Code P0502 is a vehicle
speed sensor circuit low. It is on the tail end of the trans.(or transfer case if 4wd) That does
play a part in the shifting patterns and abs system. First thing you need to do is get the
ABS computer scanned for codes as well, that is the key to start diagnosis. Grinding in the
brakes may be just normal brake problem, but if abs activation is what you feel, then a
problem in one of the front speed sensors is most likely cause. Need to get to a repair shop
and have all these different systems checked out.
Engine size = 350
ABS and Check engine light
codes = P0502
tech = mw
question = I was driving and the ABS light came on. When I applied the brakes the started
grinding. Afterwards the transmission started slipping and wouldn't shift higher than third at
3000 rpm's. Does the speed sensor control the shift rate of the tranny and if so how do I
replace it.
MW:
Hello and welcome. Sounds like you have multiple problems here. Code P0502 is a vehicle
speed sensor circuit low. It is on the tail end of the trans.(or transfer case if 4wd) That does
play a part in the shifting patterns and abs system. First thing you need to do is get the
ABS computer scanned for codes as well, that is the key to start diagnosis. Grinding in the
brakes may be just normal brake problem, but if abs activation is what you feel, then a
problem in one of the front speed sensors is most likely cause. Need to get to a repair shop
and have all these different systems checked out.
99 Chevy Monte Carlo 3.1L V6.
Question = Whenever the a/c heater is set on defrost or the passenger compartment and you accelerate
or go up a hill at 2000 rpms or more it starts blowing on the floor. Then when you are cruising it goes
back to normal. I noticed under the dash someone bypassed a vacuum line. Is this a blend door, control
head or vacuum problem.
Answer: Yeah, you're obviously loosing vacuum, or the vacuum signal is getting routed the wrong way.
With the changes in rpm or load on the engine, the vacuum pressure changes as well and if not routed
correctly, or not connected properly to the back of the control head, you will lose it and the mode
door/actuator will change to it's default position with is probably the floor setting. If you say someone
bypassed a vacuum line, I would get that corrected first and see if that fixes your problem. If not, you could
have bad control head, or bad actuator. I would bet, though, that it is just a vacuum problem.
Question = Whenever the a/c heater is set on defrost or the passenger compartment and you accelerate
or go up a hill at 2000 rpms or more it starts blowing on the floor. Then when you are cruising it goes
back to normal. I noticed under the dash someone bypassed a vacuum line. Is this a blend door, control
head or vacuum problem.
Answer: Yeah, you're obviously loosing vacuum, or the vacuum signal is getting routed the wrong way.
With the changes in rpm or load on the engine, the vacuum pressure changes as well and if not routed
correctly, or not connected properly to the back of the control head, you will lose it and the mode
door/actuator will change to it's default position with is probably the floor setting. If you say someone
bypassed a vacuum line, I would get that corrected first and see if that fixes your problem. If not, you could
have bad control head, or bad actuator. I would bet, though, that it is just a vacuum problem.
