ECM not reading vehicle speed

2009 HYUNDAI ACCENT

125,000 MILES • 1.6L • 4 CYL • 2WD • AUTOMATIC

TIM LISS

MEMBER
2 POSTS
FOLLOW

After taking a exit off of interstate, the check engine light illuminated. Went and had it scanned at local Autozone and was told it was "vehicle/transmission speed sensor". I replaced both the input and output sensors located on transmission. After maybe sixty miles, check engine light illuminates again. This time I go have it hooked up to a computer scanner. While driving the car down the road the ECM is showing that I am going zero mph. Is it the ABS wheel speed sensor that sends that information to the ECM or does someone know which sensor sends that information?

Feb 6, 2017 at 8:29 PM

HMAC300

CERTIFIED EXPERT
48,601 POSTS

the transmission sends the vehicle speed, however this may be a shorted wire or poor connection the ECM may not be getting the signal so it could be a wiring or computer problem.

Feb 7, 2017 at 6:38 AM

TIM LISS

MEMBER
2 POSTS

Thanks for your reply. I forgot to mention that the speedometer and rpm gauge seems to work fine just not getting to ECU.

Feb 8, 2017 at 2:40 AM

STRAILER

CERTIFIED EXPERT
53,872 POSTS

Hey Tim,

It sounds like you have a broken wire, here is a wiring diagram and a guide to help you check the problem further. It the wiring checks out check for voltage output at the sensor and if seems like that it working then the ECM is bad and needs replacement.

https://www.2carpros.com/articles/how-to-check-wiring

Please run some tests and get back to us so we can continue helping you.

Best, Ken

Images (Click to enlarge)

Feb 13, 2017 at 9:24 AM