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Code P0502, vehicle speed sensor "a" low, Hold warning light blinking and Check Engine Light on?

Tiny
MALLYBOY
  • MEMBER
  • 2013 CHEVROLET AVEO
  • 1.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 75,678 MILES
This vehicle, when cold after cranking, will be driving fine and when hot, it stops shifting gears and when I diagnosed it, it shows P0502: Vehicle Speed Sensor. Then I disconnected the sensor connector and checked for power using test lamp, there was power, and I used DMM and checked for signal and there was 10.50-volts on signal line of the connector. Then I checked for ground, and there was ground. Could it be the speed sensor being faulty? And how do I remove it from the transmission?
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Friday, January 27th, 2023 AT 1:08 PM

9 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

I would be happy to help, but I need some confirmation. According to my manual, the code is specific to a manual transmission. See pic 1 below.

I'm not sure if by accident you selected automatic, so let me know. If it is a manual, the diagnostics are provided. Let me know which you have, and I see what I can find on the output speed sensor.

Take care,

joe

See pics below.
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Saturday, January 28th, 2023 AT 9:38 PM
Tiny
MALLYBOY
  • MEMBER
  • 309 POSTS
Hi,

The vehicle has an automatic transmission.
I take out time to inspect the vehicle yesterday and I came with the following observations
1. I unplugged the Input Shaft Speed Sensor, and the hold warning lamp went off and when you crank and engage gear, the gear will engage smoothly without hard shift.
2. I also noticed that the 2-fault codes that normally return back are P0502 and U0100- lost communication with TCM/ECM.
So, I need a communication diagram of TCM and ECM together with junction connector X105 and X205 location, let me trace out where communication fails.
Thanks
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Saturday, January 28th, 2023 AT 10:24 PM
Tiny
MALLYBOY
  • MEMBER
  • 309 POSTS
Hi!
There's a short to voltage between the input shaft speed sensor and the transmission solenoid. I need a diagram of the transmission solenoids and for input shaft speed sensor to separate them and solve the problem.
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Sunday, January 29th, 2023 AT 12:42 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

The only schematics I have are the OEM ones. Take a look through what I attached and let me know if that is what you needed.

Take care,

Joe
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Sunday, January 29th, 2023 AT 3:13 PM
Tiny
MALLYBOY
  • MEMBER
  • 309 POSTS
This didn't show how cables run from TCM to solenoid assembly and how they enter into each solenoid.
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Sunday, January 29th, 2023 AT 11:05 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Are you looking for a schematic or a routing diagram?

Joe
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Monday, January 30th, 2023 AT 4:23 PM
Tiny
MALLYBOY
  • MEMBER
  • 309 POSTS
Routing diagram, the p0502 always returns.
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Monday, January 30th, 2023 AT 9:17 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

As far as routing through the vehicle, I have no manual that provides that information. Also, the code you provided only shows up for a manual transmission, so I asked the boss. He questioned if it is a Sonic, but the code still comes up for a manual transmission.

I attached schematics for an automatic transmission. Let me know if it helps.

Joe

See pics below.
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Tuesday, January 31st, 2023 AT 5:42 PM
Tiny
MALLYBOY
  • MEMBER
  • 309 POSTS
This diagram is not bright, try to brighten it and resend it and resend.
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Tuesday, January 31st, 2023 AT 9:41 PM

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