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84-87 ECM conversion HELP

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EyeTalk2Trees

New Member
Joined
May 29, 2001
Messages
185
I've had mine changed over, I had conely do it last year, its been working fine, Now I've changed the cam and bunch of stuff I'm putting it together and I'm having a problem connecting the harness back. THe two large plugs from the FI harness go to the ecm (The three wire, and the Four wire connectors)? Also the two connectors comming from the ECM they go to the cam and crank sensor? THis is how i have it, I don't want to start it for fear of messing somehting up,

IS there something you skip when you have the conversion???

this is all i'm stuck on and the can handle the rest
 
Not sure if I fully understand the question. The converted harness should hook up no different than when it was stock. The main difference/change that took place are pin locations on the connector to the igniton module and the addition of the mat sensor wires. Also electric fan trigger wire which is optional if you have an electric fan and want it controled by the ECM.
Is there a certain connector that you are having trouble remembering where it goes?
As far as messing something up by trying to start it, I would think that would be unlikely. If its not hooked up right you will just be turning the engine. You probably wont even be producing any spark as the C3I ign mod needs signals from quite a few sensors to function. If a sensor isnt giving a signal (i.e. because of not being hooked up) you should get a malfunction code.
Maybe Im just not reading your post right. Explain a little more clearly, this should be an easy enough subject to be able to solve and help get you going ;) :)
 
When i took the intake off, I only unplugged what i needed to. With that in mind, when i went to plug it back in not everything has a matching connector. The three wire plug from the FI harness and a 3 wire plug from the ECM. You can't hook the two together cause they don't reach. So the only option i can see is that something else; cam sensor, or crank sensor is hooked up wrong.

Right now i have the connectors that come directly out of the ECM to the cam and crank, The 4 wire plug from the FI harness is connected to 4 wire connector that is out of the wire loom that runs along the front of the engine( i know it indirectly comes from the ECM too, but its easier to describe) and the 3 wire plug that comes from the same loom of wires is connected to the FI harness. I looked it up on a wiring ECM diagram i found on this MB in Hotair basics.

Originally i had it connected differently which left the 3 wire from the FI open and one from the ECM open but they couldn't reach (as stated before) the weird thing is, the one directly from the ECM was tie-wrapped tot he connector to the crank and had no matching connector. I know I didn't tie-wrap this when i took it apart, so I wondered was this like this beofre and why? Could it even have run like this? Is it suppose to not be connected?

I just want to get it right.

thanks for helping, i hope i explained myself better this time.
 
As soon as I can I will take a look at my wiring harness. My car just got buried under snow today :( .
I do know that all the connectors you have mentioned do get connected. The only connectors that dont get hooked up to anything are a couple of one-wire plugs (one brown, one green ; one is fuel pump test lead I think). Also, you mentioned two connectors tiewrapped together. I have seen the two FI connectors tied together like this before on more than one car, this is typical. Are you sure these arent your two FI connectors? I do remember on mine that the two FI connectors are next to each other (tiewrapped I think) and reach up in front of the intake behind the cam sensor. The crank and cam sensor should be sitting close to each other under the ign mod. If this isnt enough, when I take a look maybe I can get some wire colors or something that may help. I was never aware if these connectors could plug into ones other than the one they were supposed to, or not, because where they come out of the wiring harness on mine it is apparent where they go. This may be because when I 1st put the engine together I electrical taped the wiring harness up in a way that connectors went where they were supposed to.
 
wiring?

Not clear on what your problem is but you may be talking about this----the plug on your crank sensor ( not the wiring harness ) and the plug off your cam sensor will plug into each other. You have probably been bending over the fender too long. It will probably become clear today.
 
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