Description

Scania Retarder 1999 Technical Manual

If you’ve ever chased a retarder fault with a generic aftermarket PDF that tells you to ‘check the wiring’ without telling you which pin or what voltage, you know the drill. Wasted hours, wrong parts, cross-threaded bolts from guessed torque values. I’ve been turning wrenches in San Antonio for twenty-eight years, and I’ve seen guys throw tens of thousands of dollars at a truck because they didn’t have the right documentation. The Scania Retarder 1999 Technical Manual is what the factory engineers wrote when they designed the system. It’s not a translation of a translation. It’s the original OEM document, 39 pages, issued by Scania CV AB in Sweden. You need the actual configuration codes for the control unit? It’s in there. You need to know how the ABS/EBS handshake works so you don’t lock up the brakes on a grade? It’s printed on the page.

Electrical System Design – What the Manual Actually Says

Page 3 starts with the general electrical system description. The control unit is microprocessor-based, and the same hardware runs all versions. The trick is in the configuration. The manual goes into how the control unit interprets its tasks based on the configuration codes you set. If you skip that step and just swap a control unit without programming the parameters, you’ll get limp mode or no retarder at all. The design of the system includes a clutch pedal switch, brake pedal sensor, and lever sensor — all wired through the CAN bus. This is not a wiring diagram from a third-party that guessed the colors. This is Scania’s own drawing.

Brake Sensor Functions: Pedal and Lever (Page 11)

You get two pages dedicated to the brake pedal sensor and the lever sensor. Page 11 explains how the brake pedal sensor provides retarder braking proportionally to pedal travel. I’ve seen aftermarket manuals that say ‘connect to brake light switch’ — wrong. This one tells you the sensor feeds the control unit directly, and the control unit decides the braking torque. The lever sensor section on page 13 covers the hand lever position and how it interacts with the clutch pedal. If you’re wiring a new cab or retrofitting a retarder, you need the exact voltage ranges. This manual has them.

ABS/EBS Communication: Why It Matters Under Braking

System functions include a whole subsection on ABS/EBS communication. When the retarder is applying torque to the driveline and the wheel sensors detect a lockup, the ABS/EBS system has to override the retarder request. The manual describes the CAN messages and the timing. If your truck has an intermittent ‘brake lamp’ flicker or the retarder drops out under 10 mph, you’ll find the logic here. Related: The Scania ZF 8098 2005 Technical Manual – Steering Gear Specs covers the steering side, but for retarder-ABS coordination, this is the one.

Configuration Codes and Control Unit Setup

The Configuration chapter runs from page 23 to 29. It lists the configuration codes, explains what each code does, and tells you how to set the control unit as a part. If you’re replacing the retarder control unit and don’t have the original configuration from the truck, you’ll need the correct code based on the vehicle’s equipment level. The manual even covers the control unit connections on page 31 with pin assignments. No guessing. Also check out the Scania GRS900 1997 Technical Manual – Factory Description of Operation if you’re working on the gearbox side.

Warning System and Fault Indication (Page 37)

Warning lamp, fault indication, and resetting the system are on pages 37-38. The warning system is integrated into the control unit. It monitors sensors, communication with EDC and ABS/EBS, and internal faults. The manual gives you the procedure to read blink codes and reset after repair. I’ve had techs come to me saying ‘the retarder warning light is on and I can’t clear it’ — and they didn’t realize you have to hold the diagnostic button for 6 seconds while cycling the ignition. It’s in the manual.

Engine Brake Program (MBP) and Exhaust Brake Interaction

There’s a section on MBP (engine brake program) output and exhaust brake coordination. The retarder, exhaust brake, and engine compression brake all have to work together. The manual explains the hierarchy: when the retarder is active, the exhaust brake is disabled, and vice versa. If you’re retrofitting a retarder into a truck that didn’t come with one, you’ll need to understand these interactions to avoid overheating or driveline shock. The Scania Coordinator 2001 Technical Manual – OEM Factory Specs has the full vehicle electrical integration, but for the retarder-specific logic, this 1999 manual is your foundation.

For a basic primer on how a Manual Transmission works, that’s elsewhere. But this manual doesn’t waste space on fundamentals; it gets straight into the retarder’s electrical and electronic systems. Another external resource for general transmission knowledge is Manual Transmission on Wikipedia.

Does this manual cover the mechanical rebuild of the retarder unit?

No. This is a function description and electrical technical manual. It covers the control system, sensors, communication, and configuration. For mechanical overhaul, you need the Scania Workshop Manual for the retarder unit itself.

Can I use this on a 2002 Scania with the same retarder?

It’s a 1999 publication, and the electrical architecture may differ on later model years. However, the fundamental CAN messages and sensor principles are the same up to around 2004. If your truck has the same part number control unit, the configuration codes will match. Check the manual’s control unit connection diagram against your truck’s wiring before assuming full compatibility.

I don’t hand you a shop manual that leaves you guessing. Access the Factory Manual and get the actual specs Scania used when they built that retarder system. Your time on the hoist is worth more than a third-party PDF that was scanned at 72 dpi and missing half the pages.