Ensure the NC sensor (on the transmission firewall side) is properly wired and connected Source 0.5.10 .
A common cause is a loose reverse idler shaft bolt, located at the bottom-front of the transmission. Tightening this can stop the noise and potential ATF fluid leaks Source 0.5.5 . Auto Transmission Grinding/No Shift (2003 Neon): Check Fluid Level: Low ATF4 fluid is a common culprit. neon tranny tgp
If you are modifying, a popular upgrade for 1st gen Neons is swapping in a 3.94 final drive 5-speed transmission, combined with a 2.4L engine swap and a Stage 1 clutch conversion Source 0.5.7 . Ensure the NC sensor (on the transmission firewall
Based on your request regarding a solid post for a issue, here are the most relevant, actionable solutions gathered from technical forums regarding Dodge Neon/SRT-4 transmissions. Top "Solid Post" Solutions for Neon Transmissions Auto Transmission Grinding/No Shift (2003 Neon): Check Fluid
SRT-4 transmissions can run hot, causing fluid to darken quickly. Frequent fluid changes are recommended if performance driving is involved Source 0.5.11 . Performance Modification Note
If the shifter has too much play, or the transmission gets stuck in 1st/2nd, check the shifter cables and bushings. The bushing often breaks, requiring a replacement Source 0.5.12 .
Check for bent or stretched shifter cables.