What is this wire?

[nicknorth11]

I may have narrowed my problem (no spark in cylinders 1 and 4) down to this wire, which should be getting power, but isn't. I have no idea what it is though. Can anyone tell me what it is or where it comes from/goes? I tested my friends car and it should be getting a constant 12v supply while the key is in the on position and while cranking.

 

[4g63awdhonda]

i am not real sure but i think it gets power from the mpi relay

 

[steve]

I may have narrowed my problem (no spark in cylinders 1 and 4) down to this wire, which should be getting power, but isn't.

i am not real sure but i think it gets power from the mpi relay

Nope. That's pin 8 the output of the Power Transistor Module to coil A that drives cylinders 1 and 4.
It should run to the tach connector in the engine bay and from there back to the coil. Sometimes guys cut off the tach connector not knowing that it's how the coil for 1 and 4 gets fired.

You see 12v on it because it's the other side of the coil's primary winding. Not seeing 12v there means the harness is damaged or the coil is bad.

One side of the primary in each coil is connected to the battery via the ignition switch. The other side runs to the PTM where the ECU switches current on and off by pulling that side of the coil to ground with the PTM. When the ECU switches off the power transistor the field in the primary collapses and the secondary causes the spark at the plugs.

Those other wires need to be soldered and insulated.

 

[nicknorth11]

So it would seem that I have either cut the wire between the ptu and the tach connector or between the tach connector and the coil pack? Sorry for the noob question, but can you tell me where the tach connector is or what it looks like so I can try to track down the broken wire?

Thanks a lot Steve.

 

[steve]

can you tell me where the tach connector is or what it looks like so I can try to track down the broken wire?

Officially called the Engine Speed Detection Connector.

http://www.dsmtuners.com/forums/art...y-electrical-connections-2.html#post151542343

The black/white wire runs to the PTM and the blue/red wire to the coil.

 

[nicknorth11]

Alright, I just found where that harness used to be. I cut it clean off. What are my options for fixing it?

 

[steve]

Come on now. What do you think you should do?

It's should be obvious at this point that there isn't a connection between the PTM and coil so you need to fix that. If all you did was cut the connector off then take the two wires and solder then together or strip them back and crimp a insulated female spade connector onto the two wires.

 

[nicknorth11]

Haha. I thought that could be the appropriate fix, but I had doubts because I figured if that were true, why is there a connector that looks like it should connect to another one? At any rate, thanks!

 

[nicknorth11]

Steve, you're my hero. I've been trying to find this problem for a long time and finally got it fixed! I really appreciate your help and willingness to spoon feed me. Thanks!

 

[Rob10_99]

Yep good call steve =)
You should put some shrink wrap on those fubar'd wires while your at it.

 

[steve]

I really appreciate your help and willingness to spoon feed me.

Help yes, but I draw the line at spoon feeding. Glad you were able to track it down.

 

[nicknorth11]

Yep good call steve =)
You should put some shrink wrap on those fubar'd wires while your at it.

I always solder and heat shrink.