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DME and TCM Replacing
 
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Pelican Technical Article:

DME and TCM Replacing

Nick Czerula

Time:

2 hours2 hrs

Tab:

$1000

Talent:

***

Tools:

5mm Allen bit

Applicable Models:

BMW X5 (2000-06)

Parts Required:

DME (engine control module) or TCM (transmission control module)

Hot Tip:

Disconnect battery to prevent damage

Performance Gain:

Properly operating control module

Complementary Modification:

Clear plugged e-box drain

BMW E53 X5 models have a sophisticated electronic control system. At the heart of the system are computers (control modules) used to make decisions based on sensor and user inputs. The engine control module (DME) and transmission control module (TCM) work in conjunction to provide the best driving experience. They share inputs and data across communication circuits. This helps to cut down on the wires and the number of sensors used. The computers are programmed with base parameters and utilize sensor inputs to make adaptations and control component outputs as needed.

When replacing your DME, a used component is not an option. In the past, we used to be able to grab a DME from a donor vehicle with a matching part number. That however is no longer the case. Late model BMWs utilize an anti-theft system preventing swapping from vehicle to vehicle. This is due to the VIN being programmed in the DME and an assigned rolling code. With that said, there are companies popping up that claim to be able to program a used DME to match your vehicle. I don't have any personal experience with this method. However, it is worth a phone call or a web search to see if it is an option for your vehicle. At the minimum, if you buy a new unit, you will have to code and program the DME. This has to be done using an advanced BMW scan tool, such as an Autologic.

The TCM is a bit different. As with a DME, I don't have experience installing a used model. I have heard that one can be installed. That is if the part numbers match exactly. If you do this, I would still suggest coding and programming it. Resetting the adaptations is a good idea as well. The donor vehicle adaptations will not be the same as your vehicle.

Remember that your car may have been serviced before and had parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve, as they grow older. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below.

Disconnect the negative battery terminal. See our tech article on battery replacing.

The DME and TCM are located below the wiper cowl trim (red arrow) on the right side of the vehicle, mounted in the e-box.
Figure 1

The DME and TCM are located below the wiper cowl trim (red arrow) on the right side of the vehicle, mounted in the e-box.

Remove the rubber seal (red arrow) from the cowl.
Figure 2

Remove the rubber seal (red arrow) from the cowl. Lift it at one end and pull it up to remove it.

Next, rotate the plastic retaining tabs (red arrows) 90° to release them.
Figure 3

Next, rotate the plastic retaining tabs (red arrows) 90 degrees to release them.

With all of the tabs released, lift the cowl trim up in the direction of the red arrow and remove the trim from the cowl.
Figure 4

With all of the tabs released, lift the cowl trim up in the direction of the red arrow and remove the trim from the cowl.

With the cowl trim removed, you now have access to the E-box.
Figure 5

With the cowl trim removed, you now have access to the E-box. Loosen the four 5mm Allen fasteners (red arrows). They will remain in the lid. Then remove the E-box lid. Lift it up and detach it from the rear tabs to remove it.

The DME is the front most mounted module and has a black electrical connector (red arrow).
Figure 6

The DME is the front most mounted module and has a black electrical connector (red arrow). The TCM is the rear most control module and has a blue electrical connector (green arrow).

To remove the DME, start by pressing the release tab on the rear of the outer electrical connectors (red arrows) and pulling the connectors up to remove it.
Figure 7

To remove the DME, start by pressing the release tab on the rear of the outer electrical connectors (red arrows) and pulling the connectors up to remove it.

Next, remove the three remaining electrical connectors (red arrows).
Figure 8

Next, remove the three remaining electrical connectors (red arrows). Press the release button (green arrow) and open the lock 90 degrees to release the connector (inset).

Move the wiring harness out of the way.
Figure 9

Move the wiring harness out of the way. Then press and hold the retaining tabs (green arrows) as you pull the DME up to remove it.

Slide the DME up to remove it from the E-box.
Figure 10

Slide the DME up to remove it from the E-box. Be sure that your new part numbers (green arrows) matches or supersedes the part numbers on your old DME. Reverse the steps to install the new DME. Code and program the DME as needed and clear the fault memory when you're done.

To remove the TCM, start by pressing the release tab on the outer electrical connector (red arrow) and pulling the connector up to remove it.
Figure 11

To remove the TCM, start by pressing the release tab on the outer electrical connector (red arrow) and pulling the connector up to remove it. Next, remove the two remaining electrical connectors (green arrows). Press the release button and open the lock 90 degrees to release the connector (inset).

Move the wiring harness out of the way.
Figure 12

Move the wiring harness out of the way. Then press and hold the retaining tabs (green arrows) as you pull the TCM up to remove it.

Slide the TCM up to remove it from the E-box.
Figure 13

Slide the TCM up to remove it from the E-box. Be sure that your new part numbers (red arrow) matches or supersedes the part numbers on your old TCM. Reverse the steps to install the new TCM. Code and program the TCM as needed and clear the fault memory when you are done.

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Comments and Suggestions:
Shawn Comments: How do you know the DME unit go bad?
August 17, 2016
  Followup from the Pelican Staff: It is malfunctioning and has power, ground and data bus to it. - Nick at Pelican Parts  
Jlow Comments: Very easy instructions guys, thanks. Now if only the relays were function labeled so we could understand their purpose. Thanks again guys.
February 23, 2016
  Followup from the Pelican Staff: I would grab a repair manual. It will have the relay locations and functions.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Beater Comments: Ill be back
November 12, 2015
  Followup from the Pelican Staff: Thanks. - Nick at Pelican Parts  
UDIN Comments: the technique you show step by step is really clear to understand but I need more to understand about as to when to install the new DME do i have to change the TMC as well FOR THE CAR TO START

please give me an answer THANKS
November 6, 2015
  Followup from the Pelican Staff: No. You will have to program the DME and EWS. - Nick at Pelican Parts  

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Page last updated: Wed 12/7/2016 02:45:03 AM