ECU Capacitor Replacement Question
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ECU Capacitor Replacement Question
Getting ready to open up my ECU and before I do it, I had a question about the type/ UF rating of the capacitors that need replaced. From my reading (I only one source...) I think i'm going to need 2x 10uf capacitors rated for 16+ volts and 1x 47uf capacitor rated for the same. will the 36v/50v rated ones suffice/ do a better job? Can anyone confirm/ deny the count and type? Don't want to pull the ECU until Its time to do the swap and capacitors are in hand, because the truck is my only daily driver. Otherwise I'd pull and check. Truck is an 87 F150, 300 i6 manual trand if it makes any difference, because I know they made multiple ECU configurations.
Post Fiend
Joined: Apr 2002
Posts: 19,311
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From: Waterloo, Iowa
50uF/MFD might be a little high for the 10uF/MFD depends where it is in the circuit. Bit unclear on your terminology. Are you wanting to replace with a 36V/50uF capacitor?
If they aren't physically too big to fit those should be fine for the other you mentioned. It's best to stick close to the capacitance rating unless you're certain it doesn't matter. Electrolytics in a circuit have a wide tolerance but 5x is pushing it. Doubling should be OK.
In addition to voltage and capacitance electrolytics have a temperature rating, I would be inclined to use 105F rated caps because they last longer. The auto environment can be pretty brutal.
If they aren't physically too big to fit those should be fine for the other you mentioned. It's best to stick close to the capacitance rating unless you're certain it doesn't matter. Electrolytics in a circuit have a wide tolerance but 5x is pushing it. Doubling should be OK.
In addition to voltage and capacitance electrolytics have a temperature rating, I would be inclined to use 105F rated caps because they last longer. The auto environment can be pretty brutal.
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Freshman User
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50uF/MFD might be a little high for the 10uF/MFD depends where it is in the circuit. Bit unclear on your terminology. Are you wanting to replace with a 36V/50uF capacitor?
If they aren't physically too big to fit those should be fine for the other you mentioned. It's best to stick close to the capacitance rating unless you're certain it doesn't matter. Electrolytics in a circuit have a wide tolerance but 5x is pushing it. Doubling should be OK.
In addition to voltage and capacitance electrolytics have a temperature rating, I would be inclined to use 105F rated caps because they last longer. The auto environment can be pretty brutal.
If they aren't physically too big to fit those should be fine for the other you mentioned. It's best to stick close to the capacitance rating unless you're certain it doesn't matter. Electrolytics in a circuit have a wide tolerance but 5x is pushing it. Doubling should be OK.
In addition to voltage and capacitance electrolytics have a temperature rating, I would be inclined to use 105F rated caps because they last longer. The auto environment can be pretty brutal.
Moderator
Joined: Jan 2001
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From: Virginia
You will have a problem with them fitting. The higher voltage are usually larger. But like was mentioned, if they do fit it will do no harm. I have never done this,, I am assuming they are the PC board type with both leads on one end. But they do sell the axial type with one lead coming out of each end, and sometimes they do use these in circuit board applications. I have never opened one up to look.
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You will have a problem with them fitting. The higher voltage are usually larger. But like was mentioned, if they do fit it will do no harm. I have never done this,, I am assuming they are the PC board type with both leads on one end. But they do sell the axial type with one lead coming out of each end, and sometimes they do use these in circuit board applications. I have never opened one up to look.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Find a schematic, or failing that, a dud unit to determine exactly what's installed. The capacitors themselves should be easy to find from Mouser or even Radio Shack. Use new manufacture from name brand like Nichicon.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Pictures in other threads and on other forums all show the caps with wires out one end.
Higher voltage rating won't hurt anything and can help protect against transient voltage spikes.
I say this as someone who has been messing with electronics all my life.
Dad was an electronics engineer for various civilian and government contractors
(Norden, Raytheon, etc...) not that I have any degree in EE.
Post pics of the leaky Caps , and the corrosion you find, okay?
Higher voltage rating won't hurt anything and can help protect against transient voltage spikes.
I say this as someone who has been messing with electronics all my life.
Dad was an electronics engineer for various civilian and government contractors
(Norden, Raytheon, etc...) not that I have any degree in EE.
Post pics of the leaky Caps , and the corrosion you find, okay?
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pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
I understand axial v/ radial. 
I am trying to put it in terms comtb can understand...
Polarity is important too.
I also can read resistor color codes in my sleep.
Sorting surplus components was my 'playtime' when I was four or five.
Now with SMD's there would be no way to determine what value anything had.
I am trying to put it in terms comtb can understand...
Polarity is important too.
I also can read resistor color codes in my sleep.
Sorting surplus components was my 'playtime' when I was four or five.
Now with SMD's there would be no way to determine what value anything had.
Thread Starter
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Freshman User
Joined: Dec 2014
Posts: 39
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Pictures in other threads and on other forums all show the caps with wires out one end.
Higher voltage rating won't hurt anything and can help protect against transient voltage spikes.
I say this as someone who has been messing with electronics all my life.
Dad was an electronics engineer for various civilian and government contractors
(Norden, Raytheon, etc...) not that I have any degree in EE.
Post pics of the leaky Caps , and the corrosion you find, okay?
Higher voltage rating won't hurt anything and can help protect against transient voltage spikes.
I say this as someone who has been messing with electronics all my life.
Dad was an electronics engineer for various civilian and government contractors
(Norden, Raytheon, etc...) not that I have any degree in EE.
Post pics of the leaky Caps , and the corrosion you find, okay?
Moderator
Joined: Jan 2001
Posts: 56,966
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From: Virginia
Should be ok. But if they are not swelled up or leaking I think I would leave them in place. Especially if you are not having any problems.
I don't like messing with things if they are working alright. Problem is, a lot of times they start messing up after I have done something to it. That's just a general statement, I have never messed with these computers before.
I don't like messing with things if they are working alright. Problem is, a lot of times they start messing up after I have done something to it. That's just a general statement, I have never messed with these computers before.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Always use the same voltage rating or better when replacing a cap. When a capacitor is said to be "leaking" that doesn't mean necessarily it's leaking electrolyte, though it always means that it no longer filters the DC ripple. A truly leaking capacitor is always replaced, but a failed capacitor doesn't always leak fluid. Common misconception. Ever heard an old radio hum real bad? The power supply capacitors are "leaky".
The only way to test them is for ESR or, leakage at their rated voltage. A DVOM will be fooled by the leakage and read higher capacitance. All this is academic - if they are 20 years old just replace them and fuggedaboutit.
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They're all bulged out pretty bad, did the two 47uf ones with better voltage, but the 10uf one is just as buggered. I'd like to do it right now while I'm in, but I can't figure where they'd be running 63v from unless there was an inverter somewhere...