Jump to content

Power feed: ECU v. SAM?


Recommended Posts


I'm at the wiring stage of integrating my Thunder in to a V8 Mercedes and would like to know if there's a general preference when it comes to powering things like MAP or camshaft sensor. In the original configuration, the power is supplied from SAM module. In my Thunder I/O table and help file MAP is shown to be taking voltage from +8V output of the ECU.

Is there a preferred way? I'm using an OE camshaft but an aftermarket MAP sensor.


Edited by amg
Link to comment
Share on other sites

Most sensors on the engine such as MAP, TPS, Pressure sensors will be used with the +5v reference voltage off the ecu, NOT the +8v or 12v.

The ecu will be fed with +12-14v.

Some Hall type crank and cam sensors will use the +8v regulated output off the ecu, but some will use the +12-14v for a reference(GM does this a lot.)

VR(variable reluctance) or mag sensors do not get powered.

Link to comment
Share on other sites

Thanks Brad. My question was more about the source of power to the sensors - Thunder or SAM module of the car. I will probably power them as they have been originally: whatever got their power from SAM, will keep getting it from SAM. It may not matter, I just wanted to hear some input. Thanks again.

Link to comment
Share on other sites

As Brad says, the important 0-5V sensors need to be powered by the ECU 5V reference supply (and grounded to the ECU sensor ground).  This would normally be MAP, TPS, APS and any pressure sensors.

Any other sensors that require 8 or 12V are less important and probably can get there power from anywhere.  It would be very unusual to have a MAP sensor needing 8V.


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...