Brown Wire Fix

After further troubleshooting of the no start issue I came to the conclusion that the "brown wire" fix was the way to go.

I don't really understand why but this is how I decided. The voltage at the battery is 12.32v and the voltage on the thick black wire going to 30/1 on the ignition switch is also exactly 12.32v - so no drop from the battery. But the brown wire reads 11.34v. That's almost a 1v drop. This reduced voltage seems to be insufficient to actuate the starter solenoid. The solenoid needs at least 12v. I proved this by touching the red starter solenoid wire with the brown wire, and then with the black wire. As soon as I touched the black wire the starter kicked in.

Given that the black wire and brown wire physically attach themselves together with the +ve battery connection on the starter stud I can only assume the 1v drop is between the starter and the ignition switch. But according to the wiring diagrams there is nothing between those two points for the brown wire. So I don't understand why there is a 1v drop on the brown wire when the black wire it shares the loom with has a 0v drop (I've obviously cleaned all the terminals with a metal file till they were all nice and shiny).

I didn't feel like taking apart the dashboard and rewiring the whole thing so I decided to just run an extra 10 AWG brown wire myself a.k.a the "brown wire fix".

As part of the main harness grommet on the firewall, there is a moulded covering for an existing hole. Its a little difficult to see but I've put a steel wire though it in this photo. It can just be pushed through.

I left the original brown wire disconnected at the ignition switch. I don't know what's causing the voltage drop so I should probably disconnect it at the starter as well. I connected my single new brown wire to #30 on the ignition switch and voila everything was working again - the car started instantly.

Ignition Switch and Starter Replacement

I noticed that the car had an intermittent stall. No hesitation, no funny sounds, nothing. And it wouldn't restart sometimes. After a bit of research online I found that these cars have troublesome ignition switches. One day it stalled and just wouldn't restart. Replacement wasn't expensive so I bought a new Lada ignition switch unit.

When I withdrew the old switch (no photo), it literally fell apart in my hand. Springs and weights just popped out of it. And the wiring had been modified to compensate. It had definitely broken in the past and someone has spent a lot of time on working around the problem. In any case, I fit the new switch and tried to start the car but got nothing. No crank. So I decided to take out the new switch and bench test it (need to do that first next time). But it wouldn't come out. The metal tab just above the steering lock was about 1/8 too long. It gut stuck under the strap that holds the steering column. Luckily, this isn't a tamper proof Mercedes-Benz lock, so I just cut the problematic pieces off with a hacksaw blade.

I tested the switch with a multimeter and this is what I found;

Key out    (III)
    INT -> 30
First pos    (0)
  Nothing/Everything disconnected. "Garage" mode.
Second pos   (1)
   30/1 -> 15
    INT -> 30
Start
   30/1 -> 15
    INT -> 30
    INT -> 50

For the sake of completeness. Here is a bit more info on the stock wiring according to the Fiat Manual.

      15 = Pink + Blue/Black
      30 = Brown (+ thin Pink)
    30/1 = Black
     INT = thin black + Blue/Red
      50 = Red 

 

Descriptions

Black       = +ve Battery and #30 on Alternator
Red        = #50 on Starter
Brown      = #30 on Starter and +ve Battery

Thin Pink   = (62) remove key indicator

Blue/Black  = (7) +B Ignition coil
Pink        = #9 Fuse (I)

Thin black  = (38) headlight switch
Blue/Red    = #2 Fuse (B)

#1 Fuse = Rosso (70) cigarette lighter
        = Viola (29) Inspection lamp 

#2 Fuse = (33) Windshield washer switch
        = (67) Windshield wiper 3pos switch

#9 Fuse = (77) back up light switch
        = (57) Handbrake light
        = (30) Stop light switch
        = (39) Fuel gauge

So the switch checked out OK. Deciding without properly diagnosing the problem, I thought it might be the starter so I went ahead and bought a new gear reduction starter. Thinking that even if it wasn't the starter, the old one is probably on its last legs anyway and a gear reduction starter would be a good upgrade. About half the weight, requires less energy but produces twice the speed. No brainer!

Another week or so goes by and I get the new starter. But just like the new ignition switch, the starter flange was machined slightly incorrectly which caused one of the 3 bolts from going into the flange as it would come in contact with the starter body. As you can see in the photo below;

Using the correct m8 45mm bolt, it only needs to clear the flange by about 2mm at most. But this will obviously vary depending on the type of lock washer used on the other end. Anyways, no big deal, I filed it down a tad and proceeded to replace the old one.

Taking the old one out wasn't too difficult. But I can see how this job could totally turn into a nightmare if one of the bolts was seized. Luckily for me this wasn't the case.

Jacked the car up from under the front cross member. Then with an assortment of extensions I got all the 3 bolts off.

In order to drop the starter, I had to turn the wheels slightly to the right in order to make room between the center link and the cross member.

With a bit of wiggling and jiggling it dropped out. And in went the new starter. Job done! But sadly this didn't fix my starting problem either! So more diagnosis to come.