INFORMATION TO ASSIST REPAIR OF WATER DAMAGE ON SAM MODULE
08-21-2013, 01:18 PM
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INFORMATION TO ASSIST REPAIR OF WATER DAMAGE ON SAM MODULE
There have been threads on how to repair a SAM module affected by external water damage which affects the connectors.
On my SAM (2005 Cabrio 450 Passion CDI), the damage was internal with corrosion eating away a number of traces.
My main symptoms were no turn signals and a right turn signal which came on when the emergency brake was applied and no right air-conditioning light. The corrosion was from water ingress on connectors N11-8 and N11-9. My problems might have been compounded by overcharging on numerous occasions a sick battery which put sulfuric acid fumes in the car.
When I took my SAM apart there was corrosion in two places on the board some of which I was able to fix with jumpers.
This fixed the air-conditioning but didn't fix the turn signals.
The worst damage was a corroded 74HC151 multiplex chip.
This chip has 8 inputs and receives the signals from switches in the car (turn signals, wipers, emergency brake etc.)
The computer scans the inputs one at a time and tells a relay whether to turn on or off.
I replaced the chip. Still no turn signals.
The fact that two things were happening at the same time for some switches indicated to me that some of the plated through holes on the circuit board had corroded which disconnected the input to the chip.
Because this is a CMOS chip, an unconnected input could make the output go either way. It is for this reason that every input on the connectors is terminated with a resistor and capacitor.
From information from Evilution and FQ101.CO.UK, I was able to determine which inputs were involved in my problems and was able to test with an Ohmmeter the input connections to the chips. These connections are shown in yellow and using an Ohmmeter should measure zero Ohms from end to end of each of the yellow lines.
http://www.FQ101.co.uk/images/450/electrical/SAM.pdf
http://www.FQ101.co.uk/how-to-guides/fo ... moval.html
http://www.FQ101.co.uk/how-to-guides/fo ... iring.html
http://www.Evilution.co.uk/index.php?id=721
On the picture of the topside of the board I have put yellow squares around the input lines and orange squares around the address lines.
The input pins on the chips themselves may then be tested for continuity to ensure that the plated through holes are OK.
All of mine were OK.
There is another way that two items could be turned on at the same time.
If the 3 address lines (Pins 9,10 and 11) were not properly connected, this also could cause a problem.
Unfortunately the address lines go through plated through holes under the chips, so I had to remove it again.
Sure enough, the plated through holes for the address lines which are under the chips were corroded and I had no idea where to connect them, but I got lucky. One of the lines was still connected and making contact with the address line of the other chip. This meant that I could connect the address lines of the two chips together above the board with jumpers.
In the pictures below taken from the Evilution site I have shown in yellow many of the input connections. There should be continuity from end to end of each yellow line. This will confirm that the plated through hole along this path is OK.
The address pins I have shown in orange. There are three and they are connected together pin to pin on each of the two chips.
Immediately after repairing my SAM module the right turn signal would blink quickly, but after about 30 seconds it slowly returned to its normal rate.
It appeared that there might have been corrosion on connector N11-9.
After 3 days of happily driving my repaired car, new symptoms appeared.
Parking brake light on
Cabrio roof opening and closing about 6 inches
Left indicator flashing
When I had removed the SAM unit I had noticed green copper oxide on the N11-8 and N11-9 connectors.
For this reason I sprayed these connectors with a contact cleaner-lubricant.
The next day my car was perfect and has remained so.
It appears that corrosion on these two connectors was also a factor in my problems.
Other threads have demonstrated corrosion and connector damage especially on the high current connectors.
Water ingression appears to be the contributing factor but any water in the car might enable an environment which contributes to corrosion.
Air-conditioning condensation would appear to be another likely factor.
On my SAM (2005 Cabrio 450 Passion CDI), the damage was internal with corrosion eating away a number of traces.
My main symptoms were no turn signals and a right turn signal which came on when the emergency brake was applied and no right air-conditioning light. The corrosion was from water ingress on connectors N11-8 and N11-9. My problems might have been compounded by overcharging on numerous occasions a sick battery which put sulfuric acid fumes in the car.
When I took my SAM apart there was corrosion in two places on the board some of which I was able to fix with jumpers.
This fixed the air-conditioning but didn't fix the turn signals.
The worst damage was a corroded 74HC151 multiplex chip.
This chip has 8 inputs and receives the signals from switches in the car (turn signals, wipers, emergency brake etc.)
The computer scans the inputs one at a time and tells a relay whether to turn on or off.
I replaced the chip. Still no turn signals.
The fact that two things were happening at the same time for some switches indicated to me that some of the plated through holes on the circuit board had corroded which disconnected the input to the chip.
Because this is a CMOS chip, an unconnected input could make the output go either way. It is for this reason that every input on the connectors is terminated with a resistor and capacitor.
From information from Evilution and FQ101.CO.UK, I was able to determine which inputs were involved in my problems and was able to test with an Ohmmeter the input connections to the chips. These connections are shown in yellow and using an Ohmmeter should measure zero Ohms from end to end of each of the yellow lines.
http://www.FQ101.co.uk/images/450/electrical/SAM.pdf
http://www.FQ101.co.uk/how-to-guides/fo ... moval.html
http://www.FQ101.co.uk/how-to-guides/fo ... iring.html
http://www.Evilution.co.uk/index.php?id=721
On the picture of the topside of the board I have put yellow squares around the input lines and orange squares around the address lines.
The input pins on the chips themselves may then be tested for continuity to ensure that the plated through holes are OK.
All of mine were OK.
There is another way that two items could be turned on at the same time.
If the 3 address lines (Pins 9,10 and 11) were not properly connected, this also could cause a problem.
Unfortunately the address lines go through plated through holes under the chips, so I had to remove it again.
Sure enough, the plated through holes for the address lines which are under the chips were corroded and I had no idea where to connect them, but I got lucky. One of the lines was still connected and making contact with the address line of the other chip. This meant that I could connect the address lines of the two chips together above the board with jumpers.
In the pictures below taken from the Evilution site I have shown in yellow many of the input connections. There should be continuity from end to end of each yellow line. This will confirm that the plated through hole along this path is OK.
The address pins I have shown in orange. There are three and they are connected together pin to pin on each of the two chips.
Immediately after repairing my SAM module the right turn signal would blink quickly, but after about 30 seconds it slowly returned to its normal rate.
It appeared that there might have been corrosion on connector N11-9.
After 3 days of happily driving my repaired car, new symptoms appeared.
Parking brake light on
Cabrio roof opening and closing about 6 inches
Left indicator flashing
When I had removed the SAM unit I had noticed green copper oxide on the N11-8 and N11-9 connectors.
For this reason I sprayed these connectors with a contact cleaner-lubricant.
The next day my car was perfect and has remained so.
It appears that corrosion on these two connectors was also a factor in my problems.
Other threads have demonstrated corrosion and connector damage especially on the high current connectors.
Water ingression appears to be the contributing factor but any water in the car might enable an environment which contributes to corrosion.
Air-conditioning condensation would appear to be another likely factor.
Last edited by smartcardriver; 08-21-2013 at 01:27 PM.
The following users liked this post:
jwb007 (09-10-2019)
The following users liked this post:
jwb007 (09-10-2019)
