2008 G35 2WD Jumpy Acceleration

[floridaman407]

Hey everyone, I’m trying to get some input on my 2008 G35s 2WD. Been fighting this issue for a while and I’m stuck. Here’s what’s going on:

Symptoms:
• Jumpy acceleration / delayed throttle response
• Harsh or weird automatic transmission shifting
• Dash lights: BRAKE, VDC OFF, SLIP come on immediately at key-on
• Check Engine Light pops up sometimes with P0733 (Gear 3 incorrect ratio)
• ABS/VDC lights stay on even after replacing sensors
• Scanner shows Brake fluid low and Battery voltage abnormal
• Oil temp gauge doesn’t rise properly, outside temp reads wrong

History / context:
• Car was driven daily overseas for ~3 years, then brought back to the US
• Previously had a faulty O₂ sensor (replaced before I started testing this)
• Front-left wheel speed sensor replaced (aftermarket) and reinstalled old sensor — lights still on immediately

What I’ve tried / observed:
1. Replaced front-left wheel speed sensor — no change
2. Tested old sensor — same result
3. Cleaned battery terminals / connectors — positive terminal is corroded inside
4. Measured battery voltage with multimeter — normal (~12.6V off, ~14V running)
5. Checked/topped brake fluid
6. Test drives: acceleration still jumpy, transmission still harsh

Suspected issues:
• Most likely: intermittent or high-resistance connection at positive battery terminal, causing ABS/VDC modules to see “battery voltage abnormal”
• Secondary: possible ground or wiring issues to ABS module / ECU
• ABS/VDC module misinterpreting voltage → triggers lights, torque reduction → secondary P0733 code

Next steps I’m planning:
• Replace the positive battery terminal (cut back cable if copper inside is corroded)
• Check negative battery cable / chassis ground
• Inspect ABS module power / ground connections
• After fixing the electrical foundation, clear codes and retest

TL;DR: Multiple dash warnings + jumpy acceleration + rough shifting, all pointing toward battery/ground issues rather than sensors or transmission, but not 100% fixed yet.

Any advice or similar experiences would be hugely appreciated!

[VStar650CL]

You can check ground integrity (and power wire integrity for that matter) with any good voltmeter. This may help you out:
keep-your-engine-on-the-ground-not-just ... 28130.html