Help please ! Questions concerning the ECU pin 8 W "Warning light"

[jjullienn]

Hi all !

My car is an ep71 swapped with a 4fte ep91 engine. Engine was working fine with the complete original ep91 4efte wiring.

This friday I wanted to get rid of all the unnecessary plugs, relay and other stuffs that are made for the interior side of the car and are not related to the engine.

To do so, I started cutting all the unconnected wires to simplify the wiring. But, I accidentally cut these small blue boxes thinking they were not connected to anything... but I unfortunatley realized later that they were connectors at that time the engine was unnable to start :sad:

To fix my mistake, I decided to look at every cut wire from those blue boxes and link them to every wire I can find with the same color. Once all the wires were connected the the engine finally started but a small smoke came out the ECU. Opening the ECU, I was able to see that some resistor connected to the pin 8 W "Warning light" was burning red. The 8 pin is linked with a Green White wire that is also connected to one of those blue boxes that I cut. So I assume I did something wrong when reinstalling those boxes.

Sorry for the very long introduction, but I needed some context, Here I go with the question:

- What the use of this pin "Warning light" is it the check engine light?

- Do I need it to run the engine fine?

- The "Warning light" wire coming out the ECU is Green White, does it means it has to be linked to this relay which has the exact same color? Do you guys know what this relay is made for?

Also, I am not planning to use the EP91 combination meter and I noticed that the ECU takes the "Speed Signal" information from a wire coming from the combination meter. Does the ECU need that signal to run the engine fine or can I remove the combination meter? What the use of the speed signal in the ECU?

Thanks guy for all your reply ! Help is greatly appreciated since I am in big big shit

[Stu]

The W pin supplies an EARTH to the check engine light in the dash cluster, there is no relay in the circuit. There is no feedback to the ecu so the engine will operate without it but you now wont be able to check for any diagnostic codes.

Edited November 22, 2016 by Stu

[jjullienn]

Thanks Stu! So the W is directly linked to the same color wire coming from te dash cluster. Good to know, I think it was getting somehow a +12V since the resistor in the ECU was turning red...

Do you have an idea of the use of the relay? I probably have to reconnect it to the blue boxes I cut since it has the same colors. If I do so I will also connect it to the interior fuse box because there is a wire with the same color. So I have another question : Do I need anything from this fuse box to operate the engine and the Ecu? If not I am pretty sure this relay is not necessary either. Big thanks to you Stu for helping out!

[Stu]

Yes I'd say you've caused the meltdown by powering it up by mistake unless something is trying to earth thru that circuit with a decent current draw causing it to burn out. Hard to tell really.

Sorry no idea about the relays, I havent ever wired a EP71 with a complete 4efte loom. I always strip the 4e or 5e engine loom back, remove all the chassis related wiring then merge that back into the factory EP70 engine loom. That way the factory EP71 fuse box and inside wiring stays the same and the engine loom becomes completely plug and play so its all nice and neat. Ive done 30+ of them now.

Good luck!

[jjullienn]

Thanks for the help ! The car seems to work right so I'll leave it that way. I reconnected te W pin to the dashcluster but got no warning engine light (which is a good sign ).

[Stu]

The warning light should come on when the key is turned to ON and then go out once its started.