Need help with tricking Honda ECU

Thread Starter

bigjoncoop

Joined Feb 1, 2019
129
I have a solenoid for transmission that is stuck partially open and the connector broke off while trying to replace. The solenoid was showing 200 ohms across the terminals which was only supposed to be 15 for factory spec. Can I put a 200 Ohm resistor across the terminals in the connector coming from the car to essentially show the computer the same thing?

Full story below if interested:

I have a 2000 Honda Accord. It's got 225,000 miles on it. Car runs great till recently it was slipping once in awhile while shifting from 1st to 2nd. The check engine light code came up as a transmission solenoid. Thankfully all five or six the solenoids are on the outside of the transmission easy to access. Replaced faulty solenoid indicated by ECU.

While testing faulty solenoid notice that continuity test showed 200 ohms. Factory spec is 15 ohms. Then realized connector was almost broken completely off. And that solenoid was stuck partially open. Which was allowing transmission to shift just enough to not notice a problem. Replaced with new solenoid and the transmission would not shift at all. So I Replaced again with faulty solenoid. In the process the connector broke off. But still with with faulty solenoid I'm able to drive the vehicle. But since connector is broken the computer is making the car go into limp mode which only allows 2nd and 3rd gear. And I have to shift manually.

Since before the connector broke completely off the computer was seeing 200 ohms which somehow allowed the computer to operate somewhat normally. Can I take a 200 Ohm resistor not sure what watt rating I should use, and put it across the connector coming from the car? Would that essentially be the same as having it plugged into the broken solenoid with the 200 ohms across its terminals? I'm assume it was working with 200 Ohms on its terminals because the solenoid was stuck partially open.

Thx
 
Last edited:

Papabravo

Joined Feb 24, 2006
14,409
I doubt that you can trick the ECU so easily. The DC resistance of the solenoid is probably one of the least relevant parameters. Why do you think it is so important? I'm also curious to know why you think the "faulty" value of 200 Ω is a better "trick" than the spec value of 15 Ω.
 

MisterBill2

Joined Jan 23, 2018
7,009
If you try the 200 ohms it ought to work, if not use 22 ohms which is a standard value. The problem is that a car computer always believes it is smarter than the driver. Are all of the coils the same resistance? That may be an education.
 

Thread Starter

bigjoncoop

Joined Feb 1, 2019
129
The problem is when I put the new solenoid in the check engine light that was on changes to a different code and the car is undriveable. You stuck in 3rd or 4th gear and will not move or shift even if I do it manually. And it shows a code for a different selonoid I went through all the solenoids on the transmission and all of them out fine and move with 12 volts. So I don't know exactly what it's wrong but since the car is so old with a quarter million miles on it I don't feel it's worth spending hundreds of dollars to have diagnosed. On top of that these Transmissions that are in this year of car are known to have problems. So the easiest solution is to put it back the way it was before I touched it but since the connector broke off the solenoid that's not an option.

So I put the old solenoid back on with the broken connector and the car is drivable but only in 2nd 3rd gear if I shift manually because the computer sees that there is no selonoid installed I guess. Because the connector coming from the car itself is just hanging. So I want to put a 200 Ohm resistor in the connector to make it believe that it's still connected to what it used to be.

Just wanted to make sure that wouldn't hurt anything before I did it. I was almost positive that it wouldn't I just wanted someone else's opinion.

And I'm assuming that the transmission shifts since the old solenoid is partially stuck open so it is allowing transmission fluid to flow or passed by it.

Thx
 

bwilliams60

Joined Nov 18, 2012
1,343
Not sure if I follow this 100%, but here is what I can offer. The solenoids are operated by the ECM and they control fluid flow by opening and closing passageways in the hydraulic system. Plugging in a 200 ohm resistor may fool the ECM but it wont satisfy the hydraulic system. Sequentially these solenoids are operated to carry out shift patterns. Not sure which solenoid it is, but must be involved in at least one gear.
Why not get the proper connector or hardwire it to the solenoid if you want to go on the cheap, and see what happens. Let us know what code you are getting and go from there?
 
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