# Transfer Case Inspection in Upland > 4WD not engaging or binding in turns? Our Upland transfer case inspection checks fluid, leaks, shifting and chain noise, then writes up what is worn. Source: https://route66autorepairshop.com/diagnostics-and-inspections/transfer-case-inspection Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** We check **fluid and leaks**, test **every drive mode** with a scan, and write down what is worn and how urgent it is. A transfer case inspection at Route 66 Auto Repair in Upland checks the gearbox that splits power between the front and rear axles on four-wheel and all-wheel-drive vehicles. Trouble shows up as a 4WD light, a mode that will not engage, a grinding noise or binding in tight turns. We check the fluid, test every mode, scan the control module and put the findings in writing. ## When to book a transfer case inspection - The 4WD or AWD light flashes, or the mode will not engage - Binding or hopping in tight parking-lot turns on dry pavement - A grinding or chain-slap noise from the middle of the truck - Fluid leaks near the back of the transmission - You are heading to the mountains or desert and have not used 4WD in a year ## How do we inspect a transfer case? First we check fluid level and condition at the fill plug. Transfer cases often use a different fluid than the transmission, and the report names the one your vehicle specifies. Metal paste on the drain plug magnet is noted, and so is any burnt smell. We check the input and output seals and the case halves for leaks. Then we test the modes. On electronic systems, we scan the transfer case module for codes and watch the shift motor's position data while selecting each mode. On manual lever systems, we check the linkage. A road test in 4WD lets us listen for chain slap. Binding in turns on dry pavement is a common sign of a worn clutch pack in AWD units or of a system stuck in 4WD. ## What the transfer case report shows - Fluid level, condition and the fluid type specified - Leaks at seals and case halves - Module codes and shift motor data on electronic units - Results of each mode test - Road test notes on chain noise or binding - Photos of leaks or metal debris ## Our transfer case inspection process 1. **Scan:** We read the transfer case and body modules for codes. 2. **Fluid and leaks:** Level, condition and seals are checked on the lift. 3. **Mode test:** Each drive mode is selected and confirmed. 4. **Road test and report:** We listen for noise and binding, then write up the results. ## What's included in a transfer case inspection - Module scan and shift motor data - Fluid level and condition check - Seal and case leak inspection - Test of each drive mode - Road test for noise and binding - Written findings with photos ## Need-now or need-later? **Need now:** - Binding in turns that strains the driveline - Very low fluid or heavy metal debris - A mode stuck engaged **Need later:** - A slow-to-engage mode that works on a second try - A light output seal seep with correct level ## How pricing and timing work The fee is stated at the counter first. A fluid service is a small job compared with chain, bearing or motor repair, and the written estimate spells out which applies. If we open the case and find more wear, we stop and ask before continuing. Fleet vehicles can carry unit numbers on invoices. AAA members save 10% on parts and labor, up to $75. ## What to read next Worn fluid leads to a [transfer case fluid change](https://route66autorepairshop.com/transmission-services/transfer-case-fluid-change). For noise, leaks or shifting problems, see [transfer case service](https://route66autorepairshop.com/transmission-services/transfer-case-service) and [transfer case chain replacement](https://route66autorepairshop.com/transmission-services/transfer-case-chain-replacement). The rest of a 4WD driveline is covered by the [drive shaft inspection](https://route66autorepairshop.com/diagnostics-and-inspections/drive-shaft-inspection) and the [differential fluid inspection](https://route66autorepairshop.com/diagnostics-and-inspections/differential-fluid-inspection). ## Frequently asked questions ### Why does my truck hop in tight turns? In part-time 4WD, the front and rear axles are locked together. On dry pavement they cannot slip, so the tires scrub and hop. If it happens in 2WD, something is stuck engaged, which we check. ### How often should I use 4WD? Many owner's manuals suggest engaging it briefly now and then, on a surface where that is safe, to keep parts moving. Check yours for the exact advice. ### Can mismatched tires hurt the transfer case? Yes. Tires of different sizes or wear levels can strain AWD and 4WD systems. We note tire differences on the report. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.