Improving poor ECU plug connections and conductivity

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My Name: user1234

Contributor
Posts: 20
Joined: Wed Nov 11, 2015 2:18 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 (8v)
Fuel Type: Diesel
Mileage: 210000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

Post

My C3 passed a few hands before I got it, and one of the first problems I noticed was that random components would stop functioning sometimes.
My first response was to take a look at the wiring under the hood, discovering the ECU, Fuse box, the power steering computer and all the sensors around the engine.
Disconnecting plugs and firmly reconnecting them solved many of the cars problems.

After doing this a couple of times you'll see it's pretty strait forward and easy.

When disconnecting an ECU plug for the tutorial below BEING GENTLE is the key to succeeding.
At no step of this guide is much force used.
The wiring isn't delicate and there's no need to worry, since using force is the only way to break something.

So let's get started re-wiring on the ECU.

In the first picture we have an ECU plug example, this one happens to be boot #3 on a Siemens ECU from a 2003 1.4 HDI 8v engine.

1. To remove a plug from the ECU:
a. Disconnect battery plus(+) quick release terminal.
b. Pull the plug upwards WITHOUT wiggling it, a little difficult, this is the part where the most force is used.
boot #3 on a Siemens ECU from a 2003 1.4 HDI 8v engine (32 pin capacity, not all are used)
boot #3 on a Siemens ECU from a 2003 1.4 HDI 8v engine (32 pin capacity, not all are used)

2. Slide the cap forwards to remove it:
a. bend the clips outwards.
a. bend the clips outwards.
a. bend the clips in picture #2 outwards.
b. slide the cap forwards and remove it.
c. Pull up the "tape sleeve" so you could lift a wire comfortably off the boot without bending it.
b. slide the cap forwards and remove it.
b. slide the cap forwards and remove it.
I'll put the rest of the steps and explanations on the pictures description below.

Let me know if this helped you please.
Always note the rows letter and columns number on paper before pulling out a connector.<br />Any changes can have a profound effect on the car that is far from fun rearranging..
Always note the rows letter and columns number on paper before pulling out a connector.
Any changes can have a profound effect on the car that is far from fun rearranging..
A hair clip is certainly the best tool I found so far for opening the boot up...<br />Double the metal at the edge or it won't work..
A hair clip is certainly the best tool I found so far for opening the boot up...
Double the metal at the edge or it won't work..
Before we can removing any wires from the boot, we must pull out the fastening rail.
Before we can removing any wires from the boot, we must pull out the fastening rail.
Roll up the &quot;tape sleeve&quot; so the connection could be lifted out of the boot without bending.
Roll up the "tape sleeve" so the connection could be lifted out of the boot without bending.
The blue squares are where the ECU pins go in.<br />The red squares are where each individual wires locking clip is.<br />There are two types of ports as you can see, the larger port always holds a different connector that usually have heavy duty wires on them.<br />Conveniently enough, the indexing is seen on the bottom too, so writing on paper your current wire index eliminates any possible confusion.
The blue squares are where the ECU pins go in.
The red squares are where each individual wires locking clip is.
There are two types of ports as you can see, the larger port always holds a different connector that usually have heavy duty wires on them.
Conveniently enough, the indexing is seen on the bottom too, so writing on paper your current wire index eliminates any possible confusion.
Our great tool ;) goes into the release clip slot, once all the way inside, the wire is ready to come out.
Our great tool ;) goes into the release clip slot, once all the way inside, the wire is ready to come out.
Gently pull out the correct wire.<br />Pull strait out, DO NOT BEND IT, it will break if you bend it a couple of times.
Gently pull out the correct wire.
Pull strait out, DO NOT BEND IT, it will break if you bend it a couple of times.
Keep the conductive gel clean and don't remove it, it's meant to be there. (I pushed it back in, but no need to go all crazy over it..)
Keep the conductive gel clean and don't remove it, it's meant to be there. (I pushed it back in, but no need to go all crazy over it..)
The connector before. (wide opening)
The connector before. (wide opening)
The connectors rail and clip (do not squash it when narrowing opening)
The connectors rail and clip (do not squash it when narrowing opening)
First pinch action.<br />When narrowing the opening be super aware of the metals movement and NEVER pinch on the edges, flat on the  surfaces only (as in the picture).<br />any funny angles can collapse the connector.
First pinch action.
When narrowing the opening be super aware of the metals movement and NEVER pinch on the edges, flat on the surfaces only (as in the picture).
any funny angles can collapse the connector.
Turn 90 degrees.<br />Second pinch action.<br />Don't pinch the clip down (in the red circle).
Turn 90 degrees.
Second pinch action.
Don't pinch the clip down (in the red circle).
The connector after is certain to make good contact with ECU pin.
The connector after is certain to make good contact with ECU pin.
Re-insert with the clip, once again I can't stress this enough, don't bend the connection. <br />Push strait in.
Re-insert with the clip, once again I can't stress this enough, don't bend the connection.
Push strait in.
Push the connector back into the slot using a tool, until a small click is heard.<br />The wire is back inside!
Push the connector back into the slot using a tool, until a small click is heard.
The wire is back inside!
Pull &quot;tape sleeve&quot; back down.
Pull "tape sleeve" back down.
Gently slide the fastening rail back into the boot.<br />Pushing strongly on a improperly seated connection will break it.
Gently slide the fastening rail back into the boot.
Pushing strongly on a improperly seated connection will break it.
Put the cap back on and reconnect the boot to the ECU.<br />Remember, DON'T wiggle it in, just push it down slowly and make sure the rubber seal doesn't pinch and tear.
Put the cap back on and reconnect the boot to the ECU.
Remember, DON'T wiggle it in, just push it down slowly and make sure the rubber seal doesn't pinch and tear.
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My Name: C3CAR

Guru
Posts: 2658
Joined: Wed May 04, 2011 10:01 am
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 140000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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Post

user1234 wrote:My C3 passed a few hands before I got it, and one of the first problems I noticed was that random components would stop functioning sometimes.
My first response was to take a look at the wiring under the hood, discovering the ECU, Fuse box, the power steering computer and all the sensors around the engine.
Disconnecting plugs and firmly reconnecting them solved many of the cars problems.

After doing this a couple of times you'll see it's pretty strait forward and easy.

When disconnecting an ECU plug for the tutorial below BEING GENTLE is the key to succeeding.
At no step of this guide is much force used.
The wiring isn't delicate and there's no need to worry, since using force is the only way to break something.

So let's get started re-wiring on the ECU.

In the first picture we have an ECU plug example, this one happens to be boot #3 on a Siemens ECU from a 2003 1.4 HDI 8v engine.

1. To remove a plug from the ECU:
a. Disconnect battery plus(+) quick release terminal.
b. Pull the plug upwards WITHOUT wiggling it, a little difficult, this is the part where the most force is used.
Great post!

If you don't have a great photographic memory taking a few photo of the wires can help should you get interrupted when putting the wires back in the plug ;)
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