how to check your ECU without removing it from car - by Yamae
#47
Driver School Candidate
hey i could use one of theses special capacitor to do a ripple test i am thinking my ecm is bad. i can only go in reverse and i have no codes poping up so i don't know where to start. i replace a solenoid that did not click as i tested it but still my problem stands. trying to figure which wire to unplug to do a manual shift test as well. any help is appreciated. I need help as i am not the best with cars but with no cash to give away to shops i must do this myself i do have a drive to get my ls 400 back i dont want to just let her sit around too long.
#48
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#49
#53
Moderator
Sorry for the poor availability.
It says 0.047uF and is only 1/10th of the recommended value of 0.47uF. Smaller the value, smaller the read out voltage. The plastic box contains 2 capacitors and using those 2 in parallel, you can get 0.094uF and is almost 0.1uF. Try measuring the ripple voltage with those 2. Depending on the impedance of the DVM (high enough such as 20Mohms or higher), it will probably be possible to read the ripple voltage although the read out value may be a bit smaller.
It says 0.047uF and is only 1/10th of the recommended value of 0.47uF. Smaller the value, smaller the read out voltage. The plastic box contains 2 capacitors and using those 2 in parallel, you can get 0.094uF and is almost 0.1uF. Try measuring the ripple voltage with those 2. Depending on the impedance of the DVM (high enough such as 20Mohms or higher), it will probably be possible to read the ripple voltage although the read out value may be a bit smaller.
#54
Stated capacitor is still out of stock. We should update the link. @Yamae any input on a good replacement to use for this test? I came up with this:
https://www.digikey.com/en/products/...2474JB/2595594
Is this a good replacement? As far as I know it's otherwise very similar. Similar Poly\metalized type made by Panasonic. The voltage rating for DC is DC63v ---> DC250v, which if I'm understanding correctly is basically a "don't go higher than this or you will get the magic white smoke and maybe fire".
I'm not an expert though so IDK if the changes to the other specifications of the capacitor mean anything for the purpose of this test.
https://www.digikey.com/en/products/...2474JB/2595594
Is this a good replacement? As far as I know it's otherwise very similar. Similar Poly\metalized type made by Panasonic. The voltage rating for DC is DC63v ---> DC250v, which if I'm understanding correctly is basically a "don't go higher than this or you will get the magic white smoke and maybe fire".
I'm not an expert though so IDK if the changes to the other specifications of the capacitor mean anything for the purpose of this test.
Last edited by 400fanboy; 12-09-23 at 08:53 PM.
#55
I'm not an expert either but I think the voltage rating is critical here. I would think anything above the 63 volts specified will work. ::shrug::
#56
Moderator
Stated capacitor is still out of stock. We should update the link. @Yamae any input on a good replacement to use for this test? I came up with this:
https://www.digikey.com/en/products/...2474JB/2595594
Is this a good replacement? As far as I know it's otherwise very similar. Similar Poly\metalized type made by Panasonic. The voltage rating for DC is DC63v ---> DC250v, which if I'm understanding correctly is basically a "don't go higher than this or you will get the magic white smoke and maybe fire".
I'm not an expert though so IDK if the changes to the other specifications of the capacitor mean anything for the purpose of this test.
https://www.digikey.com/en/products/...2474JB/2595594
Is this a good replacement? As far as I know it's otherwise very similar. Similar Poly\metalized type made by Panasonic. The voltage rating for DC is DC63v ---> DC250v, which if I'm understanding correctly is basically a "don't go higher than this or you will get the magic white smoke and maybe fire".
I'm not an expert though so IDK if the changes to the other specifications of the capacitor mean anything for the purpose of this test.
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BNastee (12-12-23)
#57
Oh okay. I know nothing about electrical anything, so even that post I am not confident about what is\isn't suitable.
But as long as it's a fluid film type, and is above that minimum voltage requirement you can have a lot of flexibility of what to use for the test? Thanks!
I will be ordering the one I linked and testing my ECU then. Should have done this many moons ago.
But as long as it's a fluid film type, and is above that minimum voltage requirement you can have a lot of flexibility of what to use for the test? Thanks!
I will be ordering the one I linked and testing my ECU then. Should have done this many moons ago.
#58
I'm probably stupid and missing something, but uhh what do I do when there are no wires in the diagnostic port...?
#59
I was wondering the same thing about missing terminals. Over the years, I've noticed that the terminals in this connector come and go depending on model years and models across Lexus and Toyota.
I'll have some time later on - I'll take a look at the wiring schematics to see what "should" be there.
I'll have some time later on - I'll take a look at the wiring schematics to see what "should" be there.
#60
I was wondering the same thing about missing terminals. Over the years, I've noticed that the terminals in this connector come and go depending on model years and models across Lexus and Toyota.
I'll have some time later on - I'll take a look at the wiring schematics to see what "should" be there.
I'll have some time later on - I'll take a look at the wiring schematics to see what "should" be there.
This is from the overall wiring diagram for a 1998 LS400. I cropped the area around the DLC1 (underhood data connector). It shows what is supposed to be there; I doubt this is helpful unless it can be determined what missing terminals are jumpered and the jumper can be relocated downstream of the DLC1.
Routing of DLC1 terminals -
- +B ----> EFI Relay Contact #3
- E1 ----> Junction Connector J10 ---->
- TC ----> Air Suspension ECU and TRAC/ABS ECU
- TS <---- Air Suspension ECU and TRAC/ABS ECU
- AB <---- Air Bag Sensor Assy
- WA <---- TRAC/ABS ECU
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400fanboy (03-29-24)