Examine this Burnoff Module!
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Examine this Burnoff Module!
Followed FSM procedures for code 33, MAF Sensor.
there was no power to the MAF, so i took out the dashpad (10 minutes) and proceeded to take out the Burnoff module, which took 2 hours. 3 Screws, and one very ****ed up connector.
I was having a problem where the car would start, and run very poorly, giving a code 33. I would then open and close the hood, the vibration of the hood cleared something up somewhere.
I figured i would try a little experiment..since i had the dash pad off, i started the car and it ran like crap, just like i wanted it to. I tapped the burn off module with my hand and it cleared up, just like a hood open/close would have done.
So now here I am with the burnoff module out, but I don't know jack about electronics so someone help me
.
It appears to be just a circuit board..to me its high tech, to others its probably very basic.
here are some pictures..the only thing i can really see is what looks like something got really hot and melted or something on a few parts of the board.
another thing, it doesn't look like this is the first time that the BOM has been removed from its little metal shell, the metal shell is bent upwards by a screwdriver..maybe this was a problem before?
Thanks!
there was no power to the MAF, so i took out the dashpad (10 minutes) and proceeded to take out the Burnoff module, which took 2 hours. 3 Screws, and one very ****ed up connector.
I was having a problem where the car would start, and run very poorly, giving a code 33. I would then open and close the hood, the vibration of the hood cleared something up somewhere.
I figured i would try a little experiment..since i had the dash pad off, i started the car and it ran like crap, just like i wanted it to. I tapped the burn off module with my hand and it cleared up, just like a hood open/close would have done.
So now here I am with the burnoff module out, but I don't know jack about electronics so someone help me
.It appears to be just a circuit board..to me its high tech, to others its probably very basic.
here are some pictures..the only thing i can really see is what looks like something got really hot and melted or something on a few parts of the board.
another thing, it doesn't look like this is the first time that the BOM has been removed from its little metal shell, the metal shell is bent upwards by a screwdriver..maybe this was a problem before?
Thanks!
Last edited by Pwnage1337; Aug 19, 2009 at 05:21 PM.
Advanced
Joined: Jan 2007
Posts: 72
Likes: 0
From: Chesterfield VA
I can't tell by the pictures. Bad solder will be either a very dull silver or have a ring around the component coming through the PCB.
But the color thing doesn't work on new TV's, they have required that new electronics use a non-lead solder that is dull when first put on.
But the color thing doesn't work on new TV's, they have required that new electronics use a non-lead solder that is dull when first put on.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
Would an electronic place know exactly what is going on if i brought it to them?
edit:..just called an electronic repair place and they say that they "stay away from automotive electronics because of the extreme variations". GREAT.
edit:..just called an electronic repair place and they say that they "stay away from automotive electronics because of the extreme variations". GREAT.
Last edited by Pwnage1337; Aug 19, 2009 at 05:40 PM.
Instructor
Joined: Dec 2007
Posts: 197
Likes: 1
From: Pennsylvania
I've run into "cold solder" joints on my c4 before, but not in the burn off module personally.
Specifically, they are when the joint (silver dot on board) lifts off the board and breaks the circuit. You can't really see this and the results are intermittent open circuits.
The "burned" or darker marks look to me (especially since you believe someone has already been in there) as if someone has already tried to fix a cold solder joint issue.
A way to fix these joints is to wick away the solder on the board and re-tin the joint. This can be dangerous (for the component) as too much heat (from the soldering gun) can damage things like the transistors and those chips.
I couldn't tell you anything beyond that. If you are planning on replacing the unit anyways, I would re-tin the majority (or all) of the connections that you could, being cautious of getting stuff too hot (perhaps use a hemostat as a heat sink) and clean the contacts on that relay. There is a possibility it just may work.
Specifically, they are when the joint (silver dot on board) lifts off the board and breaks the circuit. You can't really see this and the results are intermittent open circuits.
The "burned" or darker marks look to me (especially since you believe someone has already been in there) as if someone has already tried to fix a cold solder joint issue.
A way to fix these joints is to wick away the solder on the board and re-tin the joint. This can be dangerous (for the component) as too much heat (from the soldering gun) can damage things like the transistors and those chips.
I couldn't tell you anything beyond that. If you are planning on replacing the unit anyways, I would re-tin the majority (or all) of the connections that you could, being cautious of getting stuff too hot (perhaps use a hemostat as a heat sink) and clean the contacts on that relay. There is a possibility it just may work.
Safety Car
Joined: Aug 2009
Posts: 3,751
Likes: 276
From: Melbourne, Victoria, Australia
re burn of module
Get a soldering iron and heat all the joints and put a touch more solder on
Look on ebay cause the 85 is the only vette with the burn of module and you can pick one up for small change .. new they are close to 900 us
I have a spare burn of module and Mass airflow sensor .. this has saved me spending big on something that was ok ... remember there were plenty of 85 vettes built but they wil become harder to get eventualy.
the solder joints should look shiney if not redo them .
The plug on the burn of module is a pain need a small screwdriver to lift the 4 tabs on the side of the connector .. when i first had to unplug it 
it was doing my head in !
.. no other vette connector is like it hey
good luck with fixing it !! but then again any electronics repairmann should be able to fix the soldering and replace some common parts .
Look on ebay cause the 85 is the only vette with the burn of module and you can pick one up for small change .. new they are close to 900 us
I have a spare burn of module and Mass airflow sensor .. this has saved me spending big on something that was ok ... remember there were plenty of 85 vettes built but they wil become harder to get eventualy.
the solder joints should look shiney if not redo them .
The plug on the burn of module is a pain need a small screwdriver to lift the 4 tabs on the side of the connector .. when i first had to unplug it it was doing my head in !.. no other vette connector is like it hey
good luck with fixing it !! but then again any electronics repairmann should be able to fix the soldering and replace some common parts .
Racer
Joined: May 2009
Posts: 421
Likes: 2
From: van buren ar
if you go someplace that works on electronics you should be able to get them to redo all the solder connections for pretty cheap.they may be able to test the components individually.it looks like a simple board.
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
the power maf relays in the early days were garbage being non weatherpack design. I remember them always getting hot and the coating on the wiring going into them would receed and promptly touch each other. I would first see if thats whats causing your maf to wig out and or have no power.
pretty sure you could splice in weather pack relays .... I always thought this relay you are showing is for burn off only and is only used after car is shut off. either way a repinning to the 7165 ecm would be better in many ways it is a faster ecm then your original for one. you could repin a 89 7165 to eliminate the pita cold start thing.
pretty sure you could splice in weather pack relays .... I always thought this relay you are showing is for burn off only and is only used after car is shut off. either way a repinning to the 7165 ecm would be better in many ways it is a faster ecm then your original for one. you could repin a 89 7165 to eliminate the pita cold start thing.
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Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
How hard is repinning? Depending on how much a used BOM costs, I might just have to repin the ecm..but then would I have to get a different MAF sensor because my MAF sensor is for 1985 only
Found one on the bay for 100 used, with a 30 day warranty...seems like a good deal to me
Found one on the bay for 100 used, with a 30 day warranty...seems like a good deal to me
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
From the shots you took, the solder points look pretty good on the back of the PCB card....the points with the dark spots (extra heat)seems to be the components that were soldered in by hand. For resistors and diodes in general you can pretty much tell if they are bad if they have a burnt appearance....from what I can see in the pic your's look OK. The other componets on the card will require more involved testing by someone who has knowledge of the pieces at the component level. IMHO the best thing to do would be to have someone wire the module up and test the module's outputs before proceeding further.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
From the shots you took, the solder points look pretty good on the back of the PCB card....the points with the dark spots (extra heat)seems to be the components that were soldered in by hand. For resistors and diodes in general you can pretty much tell if they are bad if they have a burnt appearance....from what I can see in the pic your's look OK. The other componets on the card will require more involved testing by someone who has knowledge of the pieces at the component level. IMHO the best thing to do would be to have someone wire the module up and test the module's outputs before proceeding further.
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
No shop is going to test that module as there are no schematics for them to work with.
I suggest you put the module back into the car and then when it runs like crap again, use a non-conductive item like a #2 pencil with an eraser and gently push on areas of the board until you find the "spot" that makes the engine run correctly. Then remove module and re-flow the solder joints in that area. Then try it again. If the circuit pad has not lifted off the board or anything bad like that, you should be able to find the cracked solder joint, fix it and be good to go.
Just use a pencil type soldering iron...not a soldering gun.
Good luck.
I suggest you put the module back into the car and then when it runs like crap again, use a non-conductive item like a #2 pencil with an eraser and gently push on areas of the board until you find the "spot" that makes the engine run correctly. Then remove module and re-flow the solder joints in that area. Then try it again. If the circuit pad has not lifted off the board or anything bad like that, you should be able to find the cracked solder joint, fix it and be good to go.
Just use a pencil type soldering iron...not a soldering gun.
Good luck.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
You probably scared the poor wussies when you said auto electronic. We do have a few of the auto electronics places in Seattle, don't know where you're at.
Just seems like a simple board, and almost any electronics place should be able to test/repair it.
I really couldn't see anything that looked obvious, but I'd almost be willing to bet it's in the connection.
Just seems like a simple board, and almost any electronics place should be able to test/repair it.
I really couldn't see anything that looked obvious, but I'd almost be willing to bet it's in the connection.
Pro
Joined: Aug 2007
Posts: 509
Likes: 8
From: Livonia Michigan
The brown areas around some of the solder connection is flux from the solder. Use a tooth brush and rubbing alcohol to clean it up. It dosent look like any burnt components on the other side of the circuit board. If you had a fine tip soldering iron you could try to touch up all the solder connections, then clean it with the alcohol and re-test. Use the resin core solder if you can find it at the electronics store and ***dont overheat the pad you are trying to solder, it will lift off the circuit board.
Advanced
Joined: Dec 2006
Posts: 53
Likes: 0
From: Newton KS
How hard is repinning? Depending on how much a used BOM costs, I might just have to repin the ecm..but then would I have to get a different MAF sensor because my MAF sensor is for 1985 only
Found one on the bay for 100 used, with a 30 day warranty...seems like a good deal to me
Found one on the bay for 100 used, with a 30 day warranty...seems like a good deal to me
