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Discussion Starter #1 (Edited)
I tested the ECM with it installed in the vehicle and got a fail when testing the Ω of the circuit of the trans solenoid. It is 6.92 K Ω and 12-16 Ω is called for. I used the body of the ECM as a ground. Is this the correct way to test ECM using the body of ECM as ground?

I took the ECM out and I get no Ω. There is no reading at all when using the body of the ECM as ground. Does the ECM need to be mounted in the car or to ground to be tested? Do the three connectors need to be plugged in to test for Ω? Is one of the electrical prongs of the ECM a ground?

Looks like I found the prong on the ECM I needed to use E9/16 of ECM to test ECM. Still a fail at 4.31 K Ω good is 11-15 Ω.


When I replace the ECM, do I need to have one out of a same year Camry or if the model number of the ECM matches my ECM, will it work?
 

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Discussion Starter #2
Looks like the 96 V6 Auto LE is year specific. LE DX XLE use the same ECM.

Before I buy one, To check Ω, does the part need to be grounded to the vehicle? I would think not as when I tested the solenoids, they were not grounded to the vehicle but I know nothing about ECM's.
 

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ECUs are static sensitive. This is mentioned someplace in the FSM. So rig a ground wire ... wrap a stranded wire around a cold water pipe, before you pick it up. If you have low humidity ... dry environment ... be extra careful.
 

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^ ... right ... touch something on the main steel chassis ... maybe a bolt or something. That ought to work. ... to discharge any static electricity.

However, if you remove the ECU from the car, you just don't want to be walking on carpet or something else like that, without taking static sensitive precautions.
 

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Discussion Starter #6
So it shouldn't make any difference if I have the ECM installed or uninstalled to check between the 2 prongs on ECM that I need to test Ω???

I assume via the FSM that E9-16 of the ECM is the ground for the solenoids as there is no ground to the ECM case when the E9 plug is unplugged. I guess I should trace where the E9-16 wire goes from the ECM to see if there is a short or corrosion there just to be sure. But as I get 6KΩ and 11-15 Ω is the OK range I am sure its the ECM.
 

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Discussion Starter #7
Got a used ECM and it didn't fix my problem.

Before I test the used ECM, is there a setting on the multi meter, when testing for ohms, that I should set the meter to for testing 11 to 15 Ω or is it okay to just leave the multi meter on auto mode?
Read somewhere that you need to set the meter to a low voltage mode when testing a ECM for resistance in Ω.
 

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If it is like a similar multi-meter ... on Amazon ... you have to press the correct function ... like resistance ... Ω ... and then the meter will autorange with respect to that measurement ... Ω, that is.
 

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Discussion Starter #9
I have it on Ω in auto mode. There are different setting in the Ohm mode. I can set it in auto mode or select it to manual setting. I never done that and not sure how to do so. Its an older digital multimeter from Radio Shack and has three different setting Voltage, Ohms and Amps

In Ohm mode there is Auto and RS mode.

In RS mode there is:
M Ω
Ω


There is a mark in led that moves from a mark in the unit with numbers 4, 40, 400, 4000
In MΩ there are 2 different setting. choice of 4 or 40
In KΩ there are 3 different setting. choice of 4 or 40 or 400
In Ω there is only one setting.

Not sure which is the low voltage Ω setting so not to damage the ECU.
 

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I think I would just try the RS mode ... that would just be some kind of manual scale adjustment it looks like.

Try setting it to the Ω scale for resistance values that are expected to be not too high ... 0 ... 100 maybe.
Then just to verify the reading switch it to kΩ and you should see basically the same number, but with a shift in decimal point or a different type of representation, but basically the same number.

Another thing to try out ... with the scale set to just Ω, is to take your test leads and touch them together. Read this resistance value ... for just the test leads ... and then subtract that number from the actual test measurement that you make on the ECU. That should give you a more accurate idea of the actual resistance that you want to know.

The only thing that would cause damage to the meter ... would be using the amps measurement scale. It used to be that there was an internal fuse that would blow ... and have to be replaced ... when you tried to put too many amps through the meter. ... However, you won't be using the amps measurement ... for what you are doing. Maybe they have designed some sort of amps protection scheme by now ... can't say for sure without looking at the meter user manual.

So, generally speaking, there really shouldn't be anything to worry about when using the resistance scale to measure the ECM resistance values.
 

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Discussion Starter #11
Not worried about the multimeter. More worried about damaging the new/used ECM.

On my ECM I got 6KΩ when the manual called for 11 to 15 Ω. Thus the reason I replaced the ECM but it didn't fix it and wan to be sure of proper testing before I check the Ω of the used ECM.
 

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Have you compared the same resistance measurement on two different ECM units?

You should be able to find the FSM listed specifications for a particular measurement.

... so give that a try. It doesn't look like you risk damaging the ECM if you take static electricity precautions ... like touching a cold water pipe connection before you pick up the ECM.

There are static protective bags available. They usually come with the purchase of any hard drive or computer CPU.
 

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Discussion Starter #13
I have resisted testing the used ECM till I make sure I test it properly. It was shipped in packing peanuts. Not sure good that is for an ECM...

The FSM calls for 11 to 15 Ω.
What I am not sure of is, do I need to have the key on or off when testing. I didn't see anything if the key is on/off when testing the ECM with meter.
 

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Discussion Starter #14 (Edited)
This is where I need help.




As you can see in the top right chart where it says

IG off
IG on
1 st or 2nd gear
3 or OD gear

There are 4 symbols to read. Ω, B+ B+ Below 1V
What does the B+ = or what is B+? Is that battery voltage?

Does the chart mean that I read when touching the E7,11 pin to the E9,16 pin with meter:
Ω for IG off
B+ for IG on?
1st/2nd = B+
3rd/OD = Below 1 V
Is this correct?

With the IG off I got 6 KΩ from E7,11 pin to the E9,16 . Same with the other 2 solenoid ECM test in the chart. All got 6KΩ instead of 11 to 15 Ω
 

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Discussion Starter #15 (Edited)
Big Question.

Do you test the ECM with the plugs unplugged or do you leave them plugged in and insert a probe into the back side of the plug?
I would assume not but better check as this is all new to me. BUT if they are not plugged in, how do they get power when you test with IG on?

I have been unplugging the the plug connector and testing off the probes on the ECM. Is that the correct way to test the ECM?



Looking at the pic, it looks like I should of been testing with the plugs plugged in. Maybe thats way I have not got proper ohms???
 

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I think I understand ... to some extent ... what you are talking about.

Each horizontal space in the chart of your previous post is just a description of one specific ECM test ... That is, there are two of the ECM pins that are described in each horizontal category. In the left column, the pin numbers are given, below that are the pin names, and below that are the wire colors that are connected to the respective pins. ... You might be interested in resistance between the two pins, or possibly voltage between the two pins, paying attention to the conditions specified for each test in the middle column space.

For example to test the resistance between solenoid S1 and ground, you would put your meter in the resistance measuring mode and connect one test lead to pin E7, 11 and the other test lead to pin E9,16. You should get something like 11 to 15 ohms, after you subtract the test lead resistance, if everything is normal.


Pin E9,16 would be the same as chassis ground. You can check this out by measuring the resistance on your meter between the E9,16 pin and the chassis ground.
The value of this test measurement should only be the resistance of the test leads when touched together. ... Maybe 1 or 2 ohms ... something like that.

The chart that you have posted gives you the standard values ... either resistance ... measured with the ignition in the off position ... or voltage, which would be measured with the ignition turned to the on position. ... with whatever other condition is appropriate in the middle description panel. The voltage which is referred to as B+ is just the 12.6 volt normal battery voltage.

The less than 1 volt spec is just that ... a voltage less than 1 volt between the two pins in that particular horizontal block.

The middle column of each horizontal category gives you the required test conditions. ... IG off ... ignition off, or IG on ... ignition on ... and then the gear position ... if that is required.

What you need to do is determine which diagnostic trouble code that you are trying to check on. If you have P0753 or P0758, then, in the FSM, a few pages down from the standard ECM chart, there is a description of how to trouble shoot that specific diagnostic trouble code.

One thing I picked up from the FSM is that you should not leave the ignition key turned on for more than 10 minutes ... probably heats up the ignition coil or something. So the thing to do would be to make your voltage measurement, record your reading someplace, and then turn the ignition key off.

Which trouble code do you have showing up? Is it P0753, P0758, or P0770 ... or something different?
 

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To answer your question about leaving the plugs in or not, that would depend on whether you are measuring resistance or voltage.

If you are doing a resistance measurement, you would unplug the connectors.

If you are doing a voltage measurement, you would have to leave the connectors plugged in and pay attention to the wire colors for the particular pin that you are looking for.

Which DTC did you say that your are getting on your code scan?
 

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Discussion Starter #18
I have Code PO753

This is what I have done so far.

I tested Ω with the plugs unplugged from ECM and removed the ECM from the vehicle and get 7 KΩ looking for 11-15 Ω. Thus the reason I got a used ECM.

I have not tested the used ECM as I have found other posts saying
"1st of, you never ohm test directly to ECU or put 12v directly to the ECU there really isnt any ECU testing. if you can pull a code and go from there. best way imo is to try a known good ECU but check all your fuses 1st because you might have blown a few if your lucky. make sure you check the huge fuses as well 20-30 amp ones that look all fancy if you have any. make sure you didnt fry any relays as well.
you can check voltage at the ecu all day long, u just dont want to use ohm testing because ohm testing means your putting voltage into the circuit and in the ecu case your putting power to it which if you dont know if 5volts or 12 volts is suppose to go in to it, u can fry the ecu. sure if you know what your doing u can perform proper testing of ecu but its not often older toyota ecu ever go bad compared to todays ecu due to toyota letting chevy i believe make them because they could be programmable."


If the quote is true, then I dont want to be testing with Ω directly to the used ecm as it may be fired. I dont know what my meter is using with its in Ohm mode to test the circuit.
 

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You don't see many ... if any ... posts in the TN forum on testing ECUs.

Maybe there is a problem ... some detail ... that needs to be addressed.

What are you going to do ... just remove the original ECU and replace it with the one that you purchased?
 

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Discussion Starter #20
I have the used ECM in the Camry right now and it didn't fix the problem.

I am going to put the old one back in and do more testing with the solenoid wires.
 
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