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Discussion Starter #1
Please help me! I desperately need help with an electrical problem in my (L.H. drive) 1997 TS Spider.

It all started with Fuse G389 (red in the attached images) blowing while I was driving, killing the engine and instrument cluster at around 100 km/h.
I got help towing the car back home and after some searching, found the blown fuse (see this thread).
After I changed it, the car started and ran for about 10-15 seconds, and then I turned it off again, so everything seemed fine. A couple of days later, when my wife was going to use that car, it started as usual, but stopped dead after just a few seconds. After this, the fuse (G389) blows every time we turn the key to "on" (turning on the power).

And since this fuse controls the Key Code Control Unit, there is no (easy?) way to start the car or to bypass this feature of the car to make it start anyway.

Now to what I have done so far:
  • I have "replaced" the fuse with a H4 bulb, to not blow a new fuse every time I turn the car on. As long as it shines bright, the problem is still there.
  • I have disconnected the Key Code Control Unit (connector N77 A and B), and the instrument cluster (connector C10 A and B), and the fuse still blows. So, the problem should be somewhere between the battery, the key cylinder and the fuse. Right?
  • I have checked all other fuses that I can find, and also the ground connectors on the engine and the gearbox, just to make sure they are all right.
I have the repair instructions manual, and the extra pages for the CCU, however they are for R.H. drive models, but so far they seem to represent what I have in my L.H. drive car as well (however mirrored in many cases).

There are a few specific things I would like to get help with:
1. Where is the G99 connector (yellow in the attached images)? I can't seem to find it, and I want to make sure it is not broken in any way. It seems to be a pretty big connector with at least 15 wires in it (if I interpret the wiring diagram correctly)...
2. What are the "diamond shaped" symbols in the wiring diagram (green in the attached image). The wire changes color here, and seems like a potential problem spot when it comes to short circuits, right?

I could also really need some advice on where and how to start looking for the source of this problem. Please, anything is welcome! I would REALLY like to be able to use the car again before the summer is over...
 

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If The fuse is blowing, it is blowing for a good reason.. there is a fault current flowing ..
I'd be careful about shorting the fuse out with bulbs etc.. It could cause the wiring to overheat..
The bodge bulb will illuminate all the time current is flowing through it .. fault or no fault.. It's just acting as a current limiting device..
You have a "short circuit to earth" somewhere, causing excessive current flow.
First thing to check is do you have the correct size fuse in there ??

Edit..
Having looked at your diagram..
The "short circuit to earth" will be AFTER the fuse and up to and including the code unit..
Disconnect the code unit plug N77a/N77b
Switch on and see if the fuse still blows..

If it does still blow.. the short is in the wiring between the fuse and the code unit .
If the fuse does not blow.. re-connect the code unit plug.. switch on .. if it blows, the short is in the code unit.

You are looking for a "short to earth" here which is an unintentional/fault connection to earth.. allowing a low resistance path to earth and therefore a high current flow which is blowing the fuse.
You will need, and know how to use a "multimeter"..


A fuse is a safety device.. They blow for a good reason and should never be bypassed

The small white diamonds are permanent wiring connections.. crimped etc.. don't worry about them yet . We need to determine if the fault is in the wiring or the code box.

Electrical fault finding is a process of deduction . Just like Sherlock Holmes..
You can't see electricity.. so you break down the circuit, eliminating possibilities until you only have one left..
Try not to guess..
 

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Discussion Starter #3
Thanks for your reply.

I have disconnected the code box (N77 A and B) and also the instrument cluster (C10 A and B), and the fuse still blows.

I'm well aware of the purpose of a fuse, and I'm not planning on or trying to bypass it, since it will probably burn the code box.

The fuse is the correct "size"; a red 10A.

I have, and know how to use, a multimeter, but I'm not at all sure of where I should start measuring and what voltage or current (obviously not more than 12V/10A) should be the correct values.

The wiring from the starter key cylinder goes into a thick bunch of "taped together" cabels above the steering rack, that branches out at different points, some going through the bulkhead to the engine comaprement, others not. This makes it very difficult to follow the cables and see where the fault might be.

I would really like to find the G99 connector, since it seems like a good point to measure if the fault is "before" or "after" that point... Looking at the wiring diagram, it looks as if it should be close to the fuse box, but I can't find any connector that seems right.

Any other suggestion on where to measure or what to look for?
 

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grab the meter put it on "Ohms" or continuity check "beep" , disconnect the code box plug .. pull the fuse.. one probe to a good earth.. the other to pin A8 on the code box harness plug..
See if you have continuity to earth or a low resistance "ohms". if you have.. the short to earth is in the wiring.. if not.. it is likely in the code box..
G88 will be under the dash somewhere..
See if there is a short to earth first..
 

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Following on from Seadarts analysis the fault appears to be between the Code box and the fuse, however have you checked on the main wiring diagram that this is the only service running through fuse 389? (I am not familiar with the Spider circuits and presume that 389 is in the main fusebox in which case there probably are others connected though perhaps not used) and also has anyone tampered with the loom, particularly if the wires go near the radio.

I do understand your situation. I had a similar obscure problem on my later model GTV but on a different fuse which exhibited the same failure characteristics that you describe. I traced mine to a short to earth in the loom on an unused spur.

I suggest that G99 may be behind the carpeted side panels in the footwell and possibly is the one mounted to the tunnel bracket (driver side on a RHD car).

On a practical note: I set my multimeter to read ohms and tested to a good chassis earth without the engine running.
Obviously my shorted wire gave the same (zero) resistance reading as touching the probes together.
When you have sorted the problem I can recommend that when convenient you remove all the vehicles electrical relays, connectors and fuses and clean and 'electrolube' the contacts - I have proved that this is well worth the effort on a car of this age as small resistances build up and sometimes fool the ECU's. with interesting and frustrating results. The large fuses on the Branch Terminal Board, under the bonnet on my GTV, seem particularly prone to corrosion.

Good luck in finding and curing the problem.
 

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Discussion Starter #6
Thanks for your input!
As far as I can find (but I'm not at all 100% sure), the G389 fuse is only used for the key code unit and the instrument cluster.
I will continue my search for the fault now, and see what I can find....

//Henrik
 

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Discussion Starter #7
I have now done some more testing and probing and found that the short is between the fuse and connector G99. Marked with blue in the attached image "CCU Wiring Diagram 2.jpg".

I started by measuring as you suggested, seadart. I disconnected all known units (Key Code Unit and instrument cluster) and measured from the code box connector to earth. As expected, there is a connection (measured as 30-50 Ohms mostly). To narrow it down even more, I really wanted to find the G99 connector.

And I finally found G99! It is above the main fuse box, very difficult to see and even more so to reach. However I managed to get it "out" a bit to be able to disconnect it. Once it was disconnected I could measure the resistance on either side and there is connection between the light-blue/red cable connector in G99 and earth (and obviously also from the orange cable in the fuse holder).

When G99 is disconnected, there is no connection between the code box connector and earth.

However, regarding Luckes2.0's question about any other service running through the G389 fuse, I found a page in the repair manual where it shows that the injection system and airbag also goes through this fuse (see attachment "Fuse G389.jpg").
As far as I can see in the repair instructions for these systems (injection and airbag), they also go through the G99 connector after the fuse, so they should be out of the equation as well, once G99 was disconnected.

When looking at these different diagrams I also noticed that they have different colors on the cables AFTER the "permanent wiring connector" (the "diamond" in the diagram), indicating that that diamond actually splits the cable to at least two at that point.

So, now I know that the problem exists between connector G99 and fuse G389. But I have no idea about how I should find the actual problem.
The cables "disappear" in to thick cable harnesses wrapped in loom tape. Is it possible to have connection to earth in such a harness? Aren't there just different signal cables in these harnesses? Or could there be connection to earth via one of these other cables? But shouldn't at least one other fuse blow as well if that was the case?

One "ugly" solution I considered was to simply connect a new cable directly from the fuse to G99, but it doesn't feel right. Then the actual problem would still exist, and might affect other things now or in the future. Right? Or what do you think?

Short summary of what happened so far:
* the fuse (G389) blew while I was driving a couple of months ago.
* I replaced the fuse, and the car started and ran for several seconds (around 10 I would guess). I turned the car of, thinking the problem was solved.
* A few days later, as I started the car, the engine started, but died after just 1-2 seconds. The fuse had blown again. Ever since, the fuse blows as soon as I turn the power on (don't even need to turn the key to "start", just "on").
 

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If you are convinced that a single wire is shorting to earth that is buried inside a loom you have three options ..
1.. replace the loom ..
2..Unwrap the loom to find and replace the faulty wire..
3.. disconnect the faulty wire at both ends and run a new replacement wire .. taping it to the outside of the loom..
It's not "ugly" as you put it . standard practice..
the first two options are a hell of a lot of work.
 

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Hello Henrick,
Just a couple of points that may or may not help you.
1/ If you look at the CCU Wiring Diagram 2 in your last post you will notice that there is a diamond symbol in the wire between the fuse G389 and connector G99 which means that there is at least one other wire involved which should be investigated using the principles suggested by Seadart.
I have presumed that fuse G389 is not in the main fusebox. If it is you need to check for connections made to other circuits via the fusebox printed circuit.

2/ The looms do carry earth wires so internal shorts are possible without other circuits being affected.
I believe this is the case on my car caused by some previous owner substituting a 20 amp fuse for a 10 amp one to 'quick fix' a fault, also, although protected by Alfa with clip-on trims, the main loom passes over several metal flanges under the facia and these may have been dislodged or the loom displaced over the years possibly chafing the wiring and shorting to chassis earth.

Your 'ugly' solution may be the only practical one if you do not find the short outside of the loom. It is a mammouth job to remove and replace the crashpad. ducting and trim to access the loom for repair.
Glad you managed to locate the G99 connector, sorry if I misled you!
 

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Discussion Starter #11
Henrik_45, thanks for the tip about connector G133a, now I'll just need to find that one as well. Too bad that the actual connectors doesn't have the name/number from the repair instructions printed on them... ;)
Looking at this picture, it looks like it is located behind the carpeting in the passenger area.
http://i1134.photobucket.com/albums/m615/pkr1/Alfa Romeo GTV Phase 1 - Retro Fit Climate Control/3 Installing the climate control unit/3-3 Electrical work/2011-11-16_14-12-38_DSC_0143.jpg

Luckes2.0, you're right that the fuse G389 is not in the main fuse box. It is a "single" fuse, with just two orange wires going to and from it. It's marked as numer 2 in the image in this post from another thread: http://www.alfaowner.com/Forum/alfa-gtv-and-916-spider/96621-diagnosis-wanted-pls-help-urgent-3.html#post8951953

How do I find the "diamond symbol" in the car? How does it look? Is it possible that that kind of permanent connector is wrapped in the loom tape?
 

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Luckes2.0, you're right that the fuse G389 is not in the main fuse box. It is a "single" fuse, with just two orange wires going to and from it. It's marked as numer 2 in the image in this post from another thread: http://www.alfaowner.com/Forum/alfa-gtv-and-916-spider/96621-diagnosis-wanted-pls-help-urgent-3.html#post8951953

How do I find the "diamond symbol" in the car? How does it look? Is it possible that that kind of permanent connector is wrapped in the loom tape?

Hi Henrik,

I once saw somewhere that Alfa described these connections as 'High frequency welded' or similar and therefore the wires would have to be detatched to allow testing.
I have never had reason to try to locate one but believe the joints to be inside the loom wrapping and would expect them to be very small and plastic encapsulated.

I am sure that you are well aware that the connector pin idents in section 55 of the Alfa repair manual give the wire colours and any changes at the 'diamonds' and also provide the individual wire destinations.
I found that these were very useful in solving the problem I had - but only after I realised that my car had a later spec. loom fitted than the year of manufacture and some of the wire colours in it were strange! I finished up drawing a wiring diagram of all the relevant circuits from what I found on MY car and eventually by tracing the wires through found the problem.
The reason I mention this negative stuff?
Please - take nothing for granted until confirmed on your vehicle!
 

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The G133a connector is the multi pin connector. see below (I assume yor Motronic is M2.10.4)

I you have the service manual as a searchable pdf file then you can follow the wirring numbers.
I have copied some pictures
 

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Yes, I have the repair manual as searchable PDF, and I have looked at the images you posted above, Henrik_45. But big thanks anyway!

The problem I have right now is to locate the G133A connector, to be able to disconnect, to see if that changes anything.

And thanks for the "warning" about not taking anything for granted, Luckes2.0. (I also have a Maserati 222E, and the biturbo Maseratis are even worse when it comes to not following the documented specification or what any specific year model is supposed to have. Sometimes it seems like every car is unique, even though they where made in the thousands...)

But back to the Alfa.
I've had no luck locating the G133a connector today. I have found some threads here at AO about this specific connector, this being most helpful: http://www.alfaowner.com/Forum/alfa-gtv-and-916-spider/293014-assistance-request-late-phase-1-twinspark-with-aircon.html
The images supplied by .:ian:. (http://starcroft.org/alfa/footwell2.JPG) shows the G133a connector (the big white one) clearly and all the cable colors correspond exactly with the spec in the image you attached, Henrik_45.

However - in my car, there is no such connector at that place (behind the carpeting in the passenger footwell, below the radio, heater and stuff). See attached image.
From the hole in the carpet my car have three cable looms; 1. the Alfa diagnostics port; 2. the big green connector, and; 3. the smaller black one.
On .:ian:.'s car there is a fourth cable loom that goes to the G133a connector. As far as I can find, the only difference between his car and mine, is that they are "mirrored" (RH drive and LH drive). They are both 2.0 ts with M2.10.4 Motronic.

I have looked around in every possible place on both sides of the center console, but I can't find any connector that looks like that. Any idea where it can be located?!?
 

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Hi Henrik,

For your consideration:

According to my interpretation of Alfas layout drawing for the LHD 1978 2.0 TS 16V in Section 55-28 Page 22 of the Alfa manual.

Fuse G389 leads to a spur (servicing the code unit N77a, the right hand Instrument connector C10a and the loom connector G133b {which appears to be somewhere up under the facia}) it then continues to loom connector G99 which if disconnected isolates the left hand Instrument connector C10b.
The code unit N77b and the Code receiver N78 appear to be on a separate circuit.

The absence of G133a conforms with what you have found on YOUR 1977 car.
If this diagram proves to match your vehicle you could find G133b to isolate G60 the injection wiring earth, S11 the Motronic Control Unit, T1 the diagnostic connector, (probably the 3 pin type) and S36 the injection relay fuse, way back in the boot.
However, from your statement "When G99 is disconnected, there is no connection between the code box connector and earth." I would suggest that the problem is the Orange/White wire in the loom between G99 and C10b?
I noticed also at one point that you mentioned a connection to the airbag circuit and I had a similar condition during my problems and decided it would be wise to disconnect the battery for safety as it did not affect testing for a short to chassis.
 

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Luckes2.0, my manual has only 20 pages in the 55-28 section.
Are you looking at a wiring diagram or a "location of components" picture of the car?

As far as I can see, they are kind of contradicting each other, but I think it is the wiring diagram that shows how things are really connected, and the "location of components" picture doesn't show the actual connections, just general locations of things and perhaps the looms...
(and I assume you mean 1997/1998, not 1977 and 1978 ;)

My chassis number is 603...., this means motronic version M2.10.4 and the updated key code solution, and there should be a g133a connector, according to the manual. So far everything I've looked at is correct according to the manual for the updated version (from chassis number 6023907), but I just can't find the g133a connector...

The orange-white cable from C10B to G99 continues to N77A, so I can't see how that is relevant when both N77A and G99 is disconnected, and I get the short to earth between G389 and G99 (pin 1).

See attached wiring diagrams that are the ones that should show how things are connected in my car.
I've attached the diagrams for the key code, motronics, air bag system and another one with the instrument cluster that shows G389 as well.
They show that the key code and airbag system go from G389 to G99, and that the motronic system go from G389 to G133a.
I can't find any indication that any connection goes from G389 directly to the instrument cluster, it also goes through G99.

So, as I see it I really need to find g133a, disconnect it, and see on what side of that connector the short to earth is located...
 

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Hi Henrik,

Unfortunately I have to be quite brief as I am packing for my holiday.

Yes, I was 20 years out in my dates and also a further year out because (on revisiting the manual) I notice that the diagram I referred to is labelled 1997! :eek:

I have done a quick photo of the screen image which unfortunately has turned out to be of poor quality. The original is located where previously stated and is in the section 'Electric System diagnosis 97' and yes it is a 'location of components' diagram but also 'should be' :rolleyes: correct. It still appears to show what I previously described and as only C10b is isolated by disconnecting G99 according to this diagram the fault should be in that part of the loom.

The lesson I am re-learning is this - take NOTHING for granted, even the ECU type unless confirmed using the diagnostic socket.

As to the wiring diagrams in the manual - you have obviously found as I did, enough similarities to inspire confidence but I also found a lot of misleading information (eg. I searched a long time for fuses in a circuit and have never found them)

I wish you luck in finding that elusive G133a connector but suspect that lateral thinking may be needed.:confused:
 

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Discussion Starter #19
Thanks Henrik_45, but I have already looked at that image, and honestly I can barely make out if G133a is supposed to be in the engine compartment, or in the passenger area. If you think you can draw any more specific conclusions from that image, please share them with me...
 

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It is not obvious but I would assume the connector is in the engine bay.

Furtermore I assume the connector is on the same loom as S29, S7, S34 and S5 so if you can locate these and follow the loom to G133a
 
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