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Q: Automatic trans 3rd gear indicator light intermittent flicker on 2007 Hyundai Elantra

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I have had my car in the dealer 3 times for a 3rd gear indicator light intermittent flicker that seems unsolvable. The dealer replaced the switch on the gearshift (which switches 4th gear into 3rd gear) and the instrument cluster. Wiring tests are good. No DTC's.

How the system is wired is power comes from the main fuse block and goes through the transmission range switch, then goes to that pin switch, which splits into 2 separate circuits (4th and 3rd) In 4th gear, the circuit goes to the instrument cluster, where when the shifter is in 3rd gear, the circuit power goes from that switch to the TCM and from the TCM to the instrument cluster. In 4th gear, the light will not flicker. In 3rd gear, it will. Since that switch on the gearshift and the cluster were replaced; would the TCM be the likely cause?
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If you have the car stopped, and you depress the O/D switch does the light come on? Is it on solid or is it flickering? Can you get it to flicker by jiggling the shifter, the O/D switch, tapping on the dashboard?
This may be a TCM, but it could be a wiring problem too. Let us know what they end up finding!
Bret, the O/D switch is not present on the gearshift. It is inside the shifter and when you slide the shifter lever sideways to the right (gated shifter) it goes from 4th to 3rd.

The dash lights are P, R, N, D, 3,2,1. Each light lights up when you have it in a particular gear and I normally drive in 3rd gear because my speeds rarely exceed 40 mph. The light up solid, but flicker as I'm driving; and it does it mostly if I let off the gas (as a bad connection) while the car is at normal operating temperature. The range switch has a P, R, N, D, 2, 1 contact points, and third is using the D circuit but splits after the range switch (by using the switch on the gearshift) and when 3rd is used, power is sent to both D and 3rd at the TCM for 3rd gear. The TCM determines when 3rd gear is used, it needs power in D and 3rd to make the trans go in 3rd. Normally, most cars have an electrical 4th gear, but Hyundai uses an electrical connection for 3rd gear on the car.

The dealer did not check the range switch, which is the likely cause due to no code; which there is a P07** code for that switch or the PCM harness. I'm thinking it is one of those, but HMA refuses to work on the car now.

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