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Discussion Starter #1
The Brake Brain that is. So far, two have failed (the original and the used replacement part lasted about six months). So now I'll be on my third one. Anyone else out there having the same issues? Carlo at Alfa of Tacoma diagnosed the original problem so I don't think there is some other underlying cause. Apparently there isn't a new replacement part so I guess I just keep taking my chances with used Brake Brains?
 

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The Brake Brain that is. So far, two have failed (the original and the used replacement part lasted about six months). So now I'll be on my third one. Anyone else out there having the same issues? Carlo at Alfa of Tacoma diagnosed the original problem so I don't think there is some other underlying cause. Apparently there isn't a new replacement part so I guess I just keep taking my chances with used Brake Brains?
I have never heard of an ABS ECU/brain failure. The specialist here has a large number of them pulled from wrecked Cromas/Themas, and never seems to sell any. May I suggest you change the modulator block as well, since this is the output for the brain, it seems that a fault there would cause damage to the output circuitry. I've never heard of a modulator (valve) block failure either - usually it's speed-sensors/wiring.

Perhaps if you could describe the circumstances leading up to the failure: occasional warning light? or just fails and light stays on? Have you tried checking resistance of sensors at connectors and also at the brain plug, to ensure there are no mysterious shorts?

I heard of a case where differently-worn tyres were sufficient to bring the warning light on, though this obviously isn't the problem in your case if it's been solved by replacing the brain (I like that term... ;))

-Alex
 

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Discussion Starter #3
I'm afraid that my reply will lack the details that will alloy you to formulate a meaningful answer; the reason is that electrical stuff baffles me (family or origin issues - eight years old waiting to go fishing for two days while Dad trouble shoots the boat trailer lights). I can turn wrenches, weld, straighten fenders and even dance the Salsa but I'm a deer in the headlights with electrical stuff. The symptom is that two idiot lights (brake related) light up on the dash everytime I press the brake pedal and there are no brake lights. New brake brain cures it... for a while. I'll mention the modulator valve block to Carlo-at-the-Alfa-repair-shop. FYI, the guys at Alfa Parts Exchange tell me that this is a very common failure.
 

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No brake lights and ABS are apples and oranges. ABS ECU "brain" is behind radio area are you sure that is what you are talking about? I suspect you are talking about Rear lamp control box under glove box.

But no brake lights is usually just a brake light bad relay behind false firewall under hood or brake pedal switch. Also both those red lights will come on if you have a bad bulb in one of the tail lights or center light.

Have you verified visually no brake lights come on when pedal pushed?
 

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Discussion Starter #5
Yes, Mr. Alfisto Steve, you're correct it is the brake brain box under the glove box, next to the footwell lamp. When I started having the problem (two idiot lights on dash) I checked for brake lights and confirmed that there where none. I replaced one of the main bulbs and a couple of the little bulbs in the center brake lamp. No difference. I've already replaced the old brain with the new/used brake brain from Alfa Parts exchange and it works fine... for now. I'm assuming your advice would be to check the relay behind the firewall and the brake pedal switch or I'll be back where I started. I'll do a search and see if I can figure out those two procedures. Thanks for the help so far.
 

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Sorry that I assumed you meant the ABS ECU. :eek: My original comments still stand: I believe the ABS ECU is very reliable. I don't think our cars (in NZ) actually have the brake lights control box, unless that is to do with the Alfa Control device (check system) in which case we must have it too, but somewhere on the driver's side of the car. Perhaps it would be possible to bypass it to obtain brake lights without bulb-failure warnings.

I think I would change all the brake light bulbs in your situation - perhaps one bulb is overloading the control box?

Sorry again for the confusion with the ABS (your modulator block will be fine).

-Alex
 

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Understanding 91-93 Brake light system

Components in system for 91-93 12v 164 (24v similiar but not exactly the same):
Battery Power 4mm Red wire from G56 terminal at false firewall - HOT AT ALL TIMES (don't need key on to work brake lights).
G1 Fuse Box 15A F15 fuse
H3 brake light switch at brake pedal
I69 brake light relay behind false firewall (should click when pedal pushed if H3 getting power and working.)
N22 Alfa Romeo Control Unit (made in France) under glove box
N44 Rear Lamps Control Unit also located under glove box
E28 center stop light
E25/E26 left and right taillights

G192 white-red wire in trunk under battery for trailer brake light (hooks to pedal switch H3 so best test point to verify pedal switch works (seperate from all other components will only verify H3 is getting power from fuse and that switch works). Use a meter or test lamp tester.
 

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Make sure you are using "European" bulbs not the standard bulbs for American cars. These will have the proper wattage and proper resistance, could be messing up your brain. ;) I have to go to Pep Boys to get these, the other stores don't care the Euro bulbs. I don't know where you live, you may have to hunt around. I may be lucky, but I have never had to replace one of those brains on my car and it has been in the family for a long time. I'm not convinced the brain is the real problem though.
Charles
 

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Just bringing this very useful thread to the fore again. I searched and found it when I couldn't find relay I69. The workshop manual is pretty useless for locating things not in the driver's footwell (and it wasn't even clear it wasn't there). The relay is mentioned in Steve's post #7 above as being behind the false firewall. More specifically, it is just to the passenger side of the big grommet harness feedthrough which is itself just next to the radiator fan fuse and starter connection block.

Michael (massively appreciative of the material here)

and I should have also mentioned this thread:

http://www.alfabb.com/bb/forums/164-168-1991-1995/47150-understanding-91-93-brake-light-system.html
 

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Brake light issue

I purchased a 164S from someone that kept replacing the N22 module (because the brake light warnings on the dash came on when the brake pedal was depressed). I inherited the problem, believed the advice given to me and purchased another N22 module. Then an N44 module. Neither helped. Bad modules? Bad wiring?

So I dug in. When the lights started to work, I tucked N22 back in and the brake lights would fail. Drop it and they would work. Then they stopped working pretty regularly. I had both modules dangling from the glovebox and whenever the brake light failure notice came on, I would give the modules a nudged with a stick. Pretty odd situation.

Then I attached probes with lights to the power wires and actually watched what happened during a failure. After much experimentation I found that it was a single power wire between N22 and N44. It wasn't easy but it sure was satisfying to diagnose this one.

Now I don't have to flick on my lights when I brake and watch people come dangerously close to my rear end.

Next - the sunroof!!
 

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I purchased a 164S from someone that kept replacing the N22 module (because the brake light warnings on the dash came on when the brake pedal was depressed). I inherited the problem, believed the advice given to me and purchased another N22 module. Then an N44 module. Neither helped. Bad modules? Bad wiring?

So I dug in. When the lights started to work, I tucked N22 back in and the brake lights would fail. Drop it and they would work. Then they stopped working pretty regularly. I had both modules dangling from the glovebox and whenever the brake light failure notice came on, I would give the modules a nudged with a stick. Pretty odd situation.

Then I attached probes with lights to the power wires and actually watched what happened during a failure. After much experimentation I found that it was a single power wire between N22 and N44. It wasn't easy but it sure was satisfying to diagnose this one.

Now I don't have to flick on my lights when I brake and watch people come dangerously close to my rear end.

Next - the sunroof!!
I think this is a better diagnosis. Since it is stuffed under the dash, wires can get bent and break internally.
I would check wires as stated. I have never (knock on wood) replaced a N22 or N44 box in any of my cars. I have only 1 that I have bypassed the box for Euro lights.

jason
 

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Like a bad penny

My brake lights issue has returned. This time it is giving me the stick.
Last time it was just a bad wire between N22 and N44. This time....????

I can hear the H3 relay click when I press the brake pedal.
I check line 3 at N22 and it read 0 volts, with or without the brake pedal depressed.

Here's the great part - when I disconnect N22 I get 5V on line 3 when pedal not depressed and 12V when the pedal is depressed. Correct behavior.

Bad N22 you say? I have a collection and tried all three. No luck.

Some sage advice as it is getting nice here in Seattle and I want to drive my beast.

B
 

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I found on my 91S that when this happened, it was always either a bulb out in the tail lights (often just poor connection), including the middle lights on the trunk lid, OR, it was the low brake fluid sender wire connections being crudded up at the reservoir under the hood. Last time it was that. Check those out.
 

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My brake lights issue has returned.
Have you confirmed that your brake lights are actually not coming on? Reason I ask this apparently silly question is that it's pretty common for the two "idiot lights" to come on when the brakes are applied, and there is otherwise not a problem.
 

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Confirmed - none of the brake lights are coming on.

I really thought I licked this problem, but now I have a tough time explaining why the voltage on line 3 is being pulled to zero.

I will check what Del suggested but those items do not account for both lights to come on the dash. The schematics are not that complex.....I'm at a loss.

B
 

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H3 Brake Light Switch, I69 Brake Light Relay

My brake lights issue has returned. This time it is giving me the stick.
Last time it was just a bad wire between N22 and N44. This time....????

I can hear the H3 relay click when I press the brake pedal.
I check line 3 at N22 and it read 0 volts, with or without the brake pedal depressed.

Here's the great part - when I disconnect N22 I get 5V on line 3 when pedal not depressed and 12V when the pedal is depressed. Correct behavior.

Bad N22 you say? I have a collection and tried all three. No luck.

Some sage advice as it is getting nice here in Seattle and I want to drive my beast.

B
Do you have 12v at N22 pin A4 white-brown wire with pedal NOT depressed and 0V with pedal pressed?
 

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Correct. A4 - 12V when not depressed and 0V when depressed.

A3 seems railed low when plugged into N22. A3 operates correctly when not plugged into N22. Changing out N22 with my spares does nothing.

Could I69 be weak?? Is that possible?

B
 

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Baby's got lights!!

I69 was bad. Swapped it out and brake lights came to life.

What a cheap fix!
 
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