Used Harley ECM, TSSM and Wiring Harness: What Has to Match Before a Used One Will Work

Electrical is the biggest shelf in our building: 1,478 parts, more than any other category. It is also where a used part is most likely to be the wrong used part. A wheel that does not fit is obvious in the driveway. An ECM from the wrong year looks identical, plugs in, and then the bike will not start because the security module does not recognize it.

This is the guide for the three parts people ask us about most: the engine control module, the turn signal security module, and the main wiring harness. As of September 13, 2026 we have 71 ECMs, 87 TSSMs and 117 main harnesses listed, plus 95 regulators, 163 coils, 52 starters and 76 gauge clusters if the problem turns out to be somewhere else.

Which brain your bike has

Harley has run four generations of engine electronics, and the module from one does not talk to the others.

Carbureted bikes: an ignition module, not an ECM

Through 2006 on Big Twins and 2006 on Sportsters, a carbureted bike has no ECM. It has an ignition module that fires the coil, and that is all. Those are simple to swap: match the year range and the engine, and it works. We have 16 ignition modules listed.

1995 to 2001 Touring: Magneti Marelli fuel injection

Harley's first production fuel injection went on the Electra Glide Ultra Classic in 1995 and stayed on injected Touring models through 2001. The Magneti Marelli ECM is its own system with its own sensors and harness. Nothing from the later Delphi bikes fits it, and it is the hardest module on this list to find. We have 6 Magneti Marelli ECMs on the shelf, from 1995 and 1996 Electra Glides and a 1996 Road King Police, at $315 to $338.

2001 to 2013: Delphi fuel injection with a TSSM

Delphi injection arrived on Softail in 2001, Touring in 2002, Dyna in 2004 and every Sportster in 2007, and it is what most of the bikes on our floor run. This is also the era of the TSSM, the Turn Signal Security Module. On a bike with the factory security option, the TSSM is the immobilizer: it holds the key-fob pairing and tells the ECM it is allowed to start the engine. Bikes without security have a plain TSM (no second S) that only runs the turn signals. Same connector, different job. We have 87 TSSMs and 21 TSMs listed.

2011 and later: CAN bus and a BCM

Softail and Dyna moved to a CAN bus electrical system in 2011, with Touring and Sportster following in 2014. On these bikes the TSSM is gone. A Body Control Module (BCM) handles the security, the turn signals, the lighting and the switch inputs, and the hand controls talk to it over the bus instead of through a wire per switch. A CAN bus ECM will not work on a pre-CAN bike and the reverse is just as true. We have 9 BCMs listed.

Why a used ECM will not just plug in on a 2001 to 2013 bike

On a security-equipped Delphi bike, the ECM and the TSSM are married. Each one stores a password that has to match the other. Put a used ECM on a bike with its original TSSM and the engine will crank but not fire, because the TSSM does not recognize the new module. The same thing happens the other way when you fit a used TSSM.

The fix is a password-learn procedure. It can be done at the bike with the ignition switch and the existing key fob, and it takes about 20 minutes of following a very specific sequence, or a dealer can do it with their diagnostic tool in a few minutes. Either way, plan for it before you buy: a used ECM or TSSM from us is a working part, but it is not a working part on your bike until it is married.

Two things follow from that:

• If your bike has a TSM (no security), there is no marriage to worry about. A used ECM of the right calibration goes straight in.
• If you are replacing the TSSM, you need your existing fob PIN. If the previous owner never wrote it down, the dealer route is the only one.

What has to match on an ECM

Same generation is the first filter. After that:

• Year range. Delphi ECMs changed several times inside 2001 to 2013. Our listings carry the donor's year and the production run it belongs to; use both. Of our 71 ECMs, 8 are from 1999-2006 donors, 37 from 2007-2013, 10 from the 2008-2016 group and 3 from 2017 and later.
• Model and calibration. An ECM carries a calibration for a specific model and engine. A 2009 Road King Police ECM (we have one, listed with its Twin Cam 103) is not the same calibration as a 2009 Ultra Classic ECM even though the part looks the same. A dealer can reflash a same-generation ECM to another calibration; a different-generation one, no.
• Throttle type on Touring. 2008 and later Touring bikes use electronic throttle control. Their ECMs expect a throttle-by-wire throttle body and a twist grip sensor. A 2007 cable-throttle ECM and a 2008 ride-by-wire ECM are not interchangeable even though both are Delphi.
• ABS. Not an ECM issue, but the same bikes: an ABS bike has an extra module and a different harness. See below.

Prices: most of our Delphi ECMs are $220 to $250. The Marelli ones are more because there are fewer of them.

What has to match on a wiring harness

The main harness is the one part where "close enough" costs you a weekend. Ours are listed by donor year and model, and the titles tell you the two things that split harnesses inside a year: ABS or non-ABS (a 2010 Electra Glide Ultra harness on the shelf is listed "NON-abs" for exactly that reason) and EFI or carb on the years where both existed. Beyond that, match:

• Model. An Ultra harness has connectors for the Tour-Pak, the lowers, the radio and cruise; a Road King harness does not. The Ultra harness can usually be fitted to a lesser model with the extra legs taped off; going the other way leaves you short of connectors.
• Year, to the generation. Our 117 main harnesses split as 9 from pre-1999 bikes, 31 from 1999-2006, 57 from 2007-2016 and the rest from 2017 on. Touring is 75 of the 117; Dyna 26; Softail and Sportster 12 each.
• Sub-harnesses. Fairing harnesses, handlebar switch harnesses and fuel pump harnesses are separate parts and change on their own schedules. If you are chasing a fault in one area, the sub-harness is often the fix, and it is a lot cheaper: main harnesses run $117 to $257, sub-harnesses well under that.

Before you buy any of these

1. Confirm the fault. A no-start on a Delphi bike is more often a bad fuel pump, a failed crank position sensor or a corroded connector than a dead ECM. ECMs rarely fail outright; harness connectors and grounds fail constantly.
2. Read the label on your existing module and match the part number where you can. Here is how to read one.
3. Check the listing's donor year, model and the ABS or EFI note in the title, then look at the photos for the connector count.
4. If it is a security bike, know your fob PIN or budget a dealer visit for the marriage.
5. Call +1 440-817-0268 with your VIN if there is any doubt. Electrical returns are the ones we would rather prevent than process.

Browse the electrical and ECU shelf, all 1,478 parts of it.

Written by the Exclusive Harley Parts team, Euclid, Ohio. Stock counts and prices are taken from our live inventory on September 13, 2026 and change daily. Electrical guidance is general; the service manual for your year and model is the authority. This article was drafted with AI assistance from our own catalog data and reviewed by our staff before publishing.