Geotab HRN-UP21Y2 Harness: Fitment, Install and Specs

What Is the HRN-UP21Y2?

The HRN-UP21Y2 is a short Geotab harness, 20 cm (8 in) long, that ties a GO device into the PSM module of a Mercedes Sprinter van, sold for global markets. It took the place of the HRN-SPRPSM in Geotab's lineup, and it always works alongside the HRN-CM24Y1-A base harness.

Think of it as the compact Sprinter option. It has no kit packaging around it, just the harness, and its job is to bring power, ground and the van's CAN data from the module behind the driver seat into the base harness. If you have been fitting Sprinters for a few years, this is the part that took over from the SPRPSM on your shelf.

The HRN-UP21Y2 carries power, ground and two CAN leads, with the yellow ignition wire capped off as Geotab's guide directs.

Which Vehicles and Devices Does the HRN-UP21Y2 Work With?

Geotab describes the harness as a PSM module connection for Mercedes Sprinters in global markets, without a chassis code or year range on the listing. Its install document refers to a 2020 Sprinter 2500 and uses Sprinter MY19 pin assignments, so those are the vans the published procedure is built around. On any other year, we compare the module connector on the van with the guide first.

The HRN-CM24Y1-A is required, and the guide names the GO9 as the device. Geotab's HRN-CP04K2 kit covers the 907 chassis with a longer harness and its own fuse kit, so the two are worth comparing when you order.

What Problem Does It Solve on the Job?

A fleet adding a handful of Sprinters wants a repeatable install that survives daily use. The module behind the driver seat is out of sight and out of reach, which suits vans that change hands between drivers or sit in shared pools. The 20 cm harness keeps the joint between the module and the base harness short and easy to tie down under the seat.

Newer Sprinters bring one more thing to manage. Geotab has flagged an incompatibility, most noticeable on 2025 and later models, that can put an information message on the dash. It is not a fault code, but drivers will ask about it. Knowing that the device can go into safe mode in MyGeotab while Geotab finishes its firmware fix lets us set expectations before the first driver calls in.

How Is the HRN-UP21Y2 Installed?

This order follows Geotab's Mercedes Sprinter guide for the HRN-UP21Y2, which requires professional installation by a certified Geotab installer or equivalent:

Unplug the GO device before any harness work begins, with the van parked and switched off.
Take out the driver seat to expose the connection points around the module.
Connect the harness power connector at its center terminal, and land the ground lead on the existing ground terminal.
Open the module connector, push the white CAN-H lead into pin 16 and the green CAN-L lead into pin 32, then close it and plug it back onto the module.
Cap off the yellow ignition wire.
Join the HRN-UP21Y2 to the OBD-II portion of the HRN-CM24Y1-A and complete the remaining wiring.
Plug in the GO9, mount it GPS antenna up and fix it with cable ties.
Start the van and wait up to five minutes while it beeps through initialization; the ignition (red), GPS (blue) and cellular (green) LEDs must all be lit. Register in MyInstall and check MyGeotab.

Geotab sets a 2 m (6.5 ft) ceiling on everything connected, and one T-harness may never feed another.

The short harness links the module and the existing ground point to the base harness, which carries the GO9.

Spec	Detail
Part number	HRN-UP21Y2
Use	PSM module connection, Mercedes Sprinter, global markets
Length	20 cm (8 in)
Replaces	HRN-SPRPSM
Requires	HRN-CM24Y1-A
Guide wiring	White CAN-H to pin 16, green CAN-L to pin 32, yellow ignition capped
Installer	Professional install required per Geotab guide
Connected length ceiling	2 m (6.5 ft)
Built in	China

What Should You Watch for When Fitting It?

Do not wire this harness from memory of a CP04A2 job: in Geotab's guides, the two Sprinter harnesses put different lead colors on pins 16 and 32. Read the colors from this harness's own guide every time. Insulate the capped yellow wire properly so it cannot short against the seat frame. Leave the device unplugged until every harness joint is made, as Geotab instructs. If a 2025 or newer van shows the dash message, check safe mode before pulling anything apart.

Which Related Harnesses Should You Compare?

HRN-CP04K2: the 907 chassis Sprinter kit with the 60 cm HRN-CP04A2 and a fuse kit.
HRN-CM24Y1-A: the base harness this connection plugs into.
HRN-GS16K22-A: the universal OBD-II T-harness kit, for vans where a module connection is not needed.

What Are Common Questions About the HRN-UP21Y2?

Is the HRN-UP21Y2 the same as the HRN-SPRPSM?

Geotab shows it superseding the HRN-SPRPSM, so an older parts list that names the SPRPSM should now be filled with the HRN-UP21Y2.

What happens to the yellow wire?

Geotab's Sprinter guide for this harness says to cap off the yellow ignition wire rather than connect it, so it is insulated and tucked away during the install.

A newer Sprinter shows a message on the dash after the install. Is that a fault?

Geotab reports that some Sprinter and Vito or Metris vans, especially 2025 and newer, can show an information message on the dashboard. Geotab says it is not a DTC or engine fault, a firmware fix is in progress, and the device can be set to safe mode in MyGeotab meanwhile.

Sprinters have crossed our path many times in 35 years of twelve-volt installs. API Signal can supply the HRN-UP21Y2 with the base harness and GO device, then handle the install on site at your yard, seat out and back in. Use 803-513-1009 to reach us, or start on Get a Quote.

Sources: Geotab Harness Identification and Application, Geotab Mercedes Sprinter HRN-UP21Y2 install guide, Geotab specific install notes. GEOTAB is a registered trademark of Geotab Inc. API Signal is an independent installer and is not Geotab.

Every Geotab Harness →All 83 harnesses and accessories by part number. Get a Quote →The HRN-UP21Y2 supplied and installed on one written quote.

Geotab HRN-UP21Y2 Harness