Description

PAT DS350 Troubleshooting Manual – Factory Specs for CM20 LMI

You are on the hook for a crane that throws a load reading error or a blank display. The machine is down. The customer is watching the clock. You pull up a third-party PDF and find generic wiring colors and a torque spec for something that doesn’t exist on a PAT DS350. That’s wasted time and a pissed-off customer. PAT DS350 Troubleshooting Manual from AutoRepairManuals is the factory document – 51 pages, no reprints, no editor’s interpretation, no “close enough.” This is what PAT put in the hands of their own field techs.

This manual covers the CM20 electrical central unit, cable reel, slip ring assembly, main board, and every sensor interface on the DS350 load moment indicator. You get the same diagnostic flowcharts, the same pin numbers, and the same pressure transducer calibration procedure that PAT uses. If you need to trace a broken length cable or figure out why the anti-two-block keeps locking the lever, the answer is in these pages – not in a forum post.

What’s Inside the 51 Pages – Section by Section

The TOC starts with General Information (page 1) that explains how the DS350 monitors crane functions. Then Section 1 – General Flowchart kicks off with seven drawings: CM20 Electrical Central Unit Box (page 14), Cable Reel (page 15), Extensions (page 16), Main Board (page 17), Mechanical Adjustment Length/Angle (page 18), and Slip Ring Unit (page 20). Each drawing is a factory schematic with component callouts and wire colors – no aftermarket guesswork. Subsequent sections walk you through Lever Lockout Activated (Section 2), Broken Length Cable (Section 3), No Display (Section 4), Anti-Two-Block Problem (Section 5), Length Reading Problem (Section 6), Load Reading Problem (Section 7), Bad Data Transfer between Console & Central Unit (Section 8), Interference Problem (Section 9), Lightbar (Section 10), and Error Code Displayed (Section 11). Appendix A gives the Setting Pressure Transducer procedure – critical for accurate load readings.

Electrical Diagnostics: The CM20 Central Unit

PAT built the DS350 around the CM20 electrical box. Drawing 1 on page 14 is the first place you go when the console shows garbage or won’t power up. The schematic shows every connector, fuse, and relay path inside that box. I’ve seen techs replace the entire central unit because they didn’t have this drawing and couldn’t find a corroded pin. That’s a $2,000 mistake. The manual also includes Drawing 4 – Main Board (page 17) with component-level detail. If you’re comfortable troubleshooting with a multimeter and an oscilloscope, you can isolate a failed voltage regulator or a blown capacitor in under thirty minutes. The manual gives you the test points and expected values. No “check for continuity” without telling you which two pins.

Anti-Two-Block and Display Problems

Section 5 – Anti-Two-Block Problem (page 26) is a prime example of why factory documentation matters. The flowchart starts with verifying the switch inputs, then walks you through the logic inside the CM20. If you skip the step about the cable reel continuity, you might replace a working slip ring. The manual also covers Section 4 – No Display (page 23) with a step-by-step voltage check from the battery through the ignition switch to the console. I’ve used this exact procedure on a Grove TM9100 and it saved a full afternoon of chasing a bad ground.

For length and load reading problems (Sections 6 and 7), the manual includes the mechanical adjustment drawings on page 18. That tells you how to set the length sensor and angle sensor mechanically before you start swapping boards. Half the “bad data transfer” complaints I see trace back to a loose cable in the CM20 box – Section 8 gives you the exact data wire pinout.

Does This Manual Cover the Load Sensor Calibration?

Yes, Appendix A (page 46) covers setting the pressure transducer. That’s the procedure for zeroing and spanning the hydraulic pressure sensor that feeds the load reading. Without it, the DS350 will display a load that’s off by 10-20% even if all the hardware is good. The appendix gives the exact resistor values and voltage ranges to confirm the transducer is working. OEM documentation from PAT is the only source that includes this – aftermarket versions leave it out to keep the page count low. You need this page if you’re recalibrating after a transducer replacement or after the crane has been sitting for months and the zero drifted.

Why Factory OEM Documentation Beats Aftermarket

PAT’s copyright notice in this manual states: “This document contains proprietary information which is protected by copyright. All rights are reserved.” That’s not a warning to scare you – it means every word and every number was written by the engineers who designed the DS350. The aftermarket manuals I’ve seen for this system contain generic wiring diagrams that don’t match the CM20 pinouts. They tell you a resistor color code that doesn’t exist on the main board. I’ve had three separate customers bring me cranes with “repaired” boards that were actually damaged by using the wrong test point from a cheap PDF. The factory manual eliminates that risk. You pay for the printing and the license, not for someone’s interpretation.

Related manuals you might also need: PAT DS350 1999 Troubleshooting Manual | Grove TM9100 Boom Control, PAT DS 105 1996 Troubleshooting Manual, PAT America DS350 TMS 870 TTS 870 2001 Troubleshooting Manual. For general manual transmission knowledge, see Manual Transmission and Manual Transmission.

Who Needs This Manual?

If you own a crane equipped with a PAT DS350 LMI – whether it’s a Grove, a Link-Belt, or a Terex – you need this manual. If you are a mobile crane technician who bills by the hour, this manual pays for itself the first time you use it to diagnose a no-display in fifteen minutes instead of three hours. Even a skilled home-garage mechanic who works on heavy equipment will find the electrical schematics clear enough to follow with a basic meter. The manual assumes you know how to use test equipment, but it doesn’t assume you know the DS350’s internal logic – that’s what it teaches you.

Q: Is this manual specific to the DS350 with CM20, or does it cover other PAT models?

This manual covers only the DS350 Load Moment Indicator paired with the CM20 electrical central unit. It does not cover the PAT DS 100 or DS 300 series. For other PAT LMI models, see the related manuals listed above.

Q: Does this manual include the full wiring harness diagram for the entire crane?

No. It includes the factory schematics for the CM20 box, cable reel, slip ring, and main board connections to the console and sensors. The harness beyond those components (e.g., cabling from the central unit to the engine ECU) is not included. You get the critical interfaces that cause 90% of electrical faults.

Q: Can I use this manual to calibrate the load sensor after replacing the transducer?

Yes.

Q: How many pages are in the manual and what format is the access?

This is a 51-page PDF format. The file name is PAT_DS350_Troubleshooting_Manual_en-29812005291.pdf. It is the original factory scan – bookmarked sections for quick navigation. No watermarks, no missing pages.

If you are still using a photocopy of a photocopy or a free PDF with pages out of order, stop wasting time. The PAT DS350 Troubleshooting Manual on AutoRepairManuals is the real document – the same one PAT shipped with the system. Access the Factory Manual and get the crane back to work with the right data in your hands.