845RE Transmission Rebuild & Repair in Glendale, AZ (Ram Jeep)

Sun West Transmissions — Glendale, AZ. Free estimates, honest diagnosis and a 3-year / 40,000-mile warranty on qualifying rebuilds and replacements.

The 845RE is Chrysler’s licensed version of the ZF 8HP45 eight-speed automatic, built for rear-wheel-drive and four-wheel-drive vehicles. It is generally paired with the 3.6L Pentastar V6 and other moderate-output engines, while higher-torque V8 applications use stronger versions of the same design such as the 8HP70-based unit. The 845RE brought smooth shifts, quick response and better fuel economy to trucks and SUVs that had used older five- and six-speed automatics.

Sun West Transmissions in Glendale diagnoses, repairs and rebuilds the 845RE for owners of Rams, Jeeps, Dodges and Chryslers across the West Valley. This is a sophisticated unit, and we treat it that way.

Vehicles with the 845RE

• Ram 1500 with the 3.6L V6 and some other engines
• Jeep Grand Cherokee with the V6
• Dodge Durango with the V6
• Dodge Charger, Dodge Challenger and Chrysler 300 with the V6

Because the 845RE and its heavier-duty siblings look alike, we confirm the exact model before ordering parts. For the related 850RE and other eight-speed units, see our 8HP50 / 850RE page.

How the 845RE Works

The 845RE uses four planetary gear sets and five shift elements, with only two of them released at each shift. That allows eight forward gears with fast, smooth shifts. Control is handled by a mechatronic unit, which combines the valve body, solenoids and transmission control electronics in one assembly inside the transmission. The mechatronic constantly adapts clutch fill and pressure to keep shifts smooth.

Common 845RE Problems

Harsh or Clunky Shifts

Some vehicles develop harsh downshifts when coming to a stop, a bump on the 1-2 shift or a delayed engagement into drive. Adaptive values, software calibration, fluid level and mechatronic wear all play a role. Our Ram 1500 eight-speed problems page goes into common Ram complaints.

Torque Converter Shudder

A vibration at steady highway speeds, especially at light throttle, often points to the converter clutch. Fluid condition is a common factor.

Fluid Leaks

The 845RE uses a plastic pan with an integrated filter, and leaks can develop at the pan, the electrical connector seal or other seals. Low fluid in an eight-speed is serious because fluid level directly affects clutch control. The pan and filter are typically replaced as a unit during service.

Mechatronic Faults

Failures in the mechatronic unit can cause warning lights, limp mode or loss of certain gears. Some faults are software related; others require component replacement and programming.

Shifter and Electronic Issues

Many 845RE vehicles use electronic shifters. Problems with the shifter, wiring or park system can cause messages, no-start in park or gear selection issues that are not inside the transmission at all.

How We Diagnose an 845RE

We scan all related modules, check software levels, review adaptations and live data, check fluid level using the correct temperature-based procedure and road test the vehicle. We also inspect for leaks at the pan and connector. Proper diagnosis often saves owners from unnecessary repairs. See our diagnostic testing page.

845RE Repair and Rebuild

Depending on the cause, repair may include a software update and adaptation reset, leak repair with a new pan and filter, mechatronic repair or replacement with programming, or a complete rebuild. A rebuild includes full disassembly, new clutches, seals and wear parts, replacement of worn hard parts, mechatronic inspection and converter service. Qualifying rebuilds include our 3-year / 40,000-mile warranty.

845RE Rebuild Cost

Cost depends on the vehicle, whether the fix is software, a leak, the mechatronic or internal parts, and on what we find. We give free estimates after diagnosis. For vehicle-specific information, see our Dodge Ram 1500, Jeep Grand Cherokee and Dodge Charger pages. Financing is available.

Maintenance Advice for Eight-Speed Owners

Some owners assume the fluid in modern eight-speeds lasts forever. In Arizona heat, with towing or heavy traffic, fresh fluid is cheap insurance. Use the correct fluid, follow the right fill procedure and have leaks fixed promptly. Our guide on synthetic transmission fluid explains why fluid quality matters.

845RE Transmission FAQ

Is the 845RE a ZF transmission?

It is based on the ZF 8HP45 design and built by Chrysler under license with calibrations for its vehicles.

Can I check the fluid with a dipstick?

No. The 845RE has no conventional dipstick. Fluid level is checked at a fill plug with the transmission at a specific temperature, usually with a scan tool.

Why does my truck clunk when slowing down?

It can be adaptive values, software, fluid level or a mechanical issue. Driveline parts can also clunk, so we check the whole system.