SkiBumDreams

checking out pcm grounds, i had already cleaned all surfaces with the dremel and checked resistance between each ground point, they all check out at .3 ohms between each point. this evening i pulled the pcm out and unhooked each connector to make sure the pins that are labeled as ground check out to a ground stud. i picked a bolt in front of the radiator.

with the key off engine off and the connectors disconnected from the pcm. all wires labeled pcm ground (conn a red-a2, a18; conn c grey c32; conn d blue d1) check out at .3 ohms. now on conn b black the schematic says b6 and b16 are sensor grounds these two wires have no continuity / infinite resistance to the ground stud. is this the case because the key is not on? or is there a problem?

what are some other wires i should check for continuity?

i am trying to troubleshoot an intermittent/very jumpy/unstable dlc connection for scanning with my laptop.

tomorrow i will check the connection between the pcm connector and the dlc connector under the dash(ran out of daylight today)

on a separate note but still a wiring question. what gauge is the engine harness wire to the oxygen sensors? to the maf?

i'd love to make my own wiring harness but i have no idea what type and where to buy the pcm connectors and their pins?

thanks for taking a look and any help you can give.

Guest47904

You made a few mistakes that are understandable.

You only listed a problem with the DLC, not any running issues.

You are sort of correct that B6 and B16 are ground but that is internal to the PCM. Not the wires them selves when the harness is pulled off. So when you pull the connector off the PCM, those wires only go to the sensors NOT to ground directly. So you would want to ohm the pins on the PCM (6 and 16) to ground. However it is NOT advisable to use an ohm meter on the PCM. Especially if you don't know what you are doing.

Next, if you are having a problem communicating, focus on the DLC, not everything else. If the connection points you pointed out were a problem, the PCM would be throwing certain DTC's. Or if it were enough grounds, it would stop the PCM from working altogether, so the engine would not even run but it would not just be effecting the communications. Unless the ground point of the DLC were disconnected.

Pin A of the DLC is connected to ground.
Pin B of the DLC is connected to Pin 20 of the Blue PCM connector. This is field service enable or diagnostic request.
Pin M of the DLC is connected to Pin 30 of the Blue PCM connector. This is the serial data.

http://www.summitracing.com/parts/PRF-65105/