atkinson40

90 Civic DX auto will not shift out of park. Took the pastic console off around the shifter to see WTF. Turn the key to "ON", do not start and watch as I press the brake pedal the solenoid activates. As soon as I start the car the solenoid deactivates and I can't shift out of park w/o manually releasing the shifter.

For good measure I replaced the brake switch but no help. Something is happening when I turn the car on but I got no clue. TIA Kevin

ezone

Just saw the other post. This might be related to that.

Check for codes.

Got a TPS code/problem?

atkinson40

No codes now EZ, but it used to set 7 once in a while and then idle fine. If I understand the ECU sequence right, it will fall back to a preset nominal idle injector PW when a code is set. This lead me to believe it is not a vacuum leak or the IAC(which I've changed anyway)

I swapped the TPS. No help. I'm going to check the voltage. I believe it should be less than .65V and then go up smoothly as I open the throttle. Thanks EZ Kevin

ezone

Code 7 = Throttle angle sensor circuit (TPS)

Yeah the reason I asked about the TPS is the ECM won't let the shifter come out of park if it thinks you have the throttle open, and it looks at the TPS value to determine that.

If you get a wiring diagram and a good service manual, you can check if the ECM is prohibiting this by measuring on the wire between the ECM and the interlock control unit. You should be able to check all the rest of the circuits involved right from the interlock control unit plug too.
The control unit is under the drivers seat..... Water damage possible? Shampoo, drinks, etc.

That car is way older than my time at this dealer, so I'm all about SWAG here...

Play around with this one, see what you can do: use a voltmeter on your TPS to measure output voltage, and adjust it to read 0.49v @ fully closed throttle, hot, (with 20" vacuum applied to dashpot dia., if applicable).
.65v is probably too high. (The manual says "about 0.5 volts", but they are extremely consistently set at exactly 0.49v on every car I do see.)
(I also don't know which type of throttle body you have on your engine, nor which engine!)



Fuse #1 and 35
Ground G-511, in the trunk......center, remove the panel it's a couple inches directly below the latch....

atkinson40

Thanks ezone,

It's the TPS. It was reading about 1.2V closed. I set it to .4V and the shifter doesn't stay locked anymore, but I've still got the idle hunting problem. As I open the throttle, the voltage only varies between .4V and about 1.8V. This is wrong. It should go all the way up to around 4.5V. I can't find the TPS for my car anywhere.

It's dual point fuel injection. I'm going to try a junkyard field trip and see if I can pink one up. Maybe I can rebuild a JY one.

I drilled a hole in the top and the bottom of the TPS and squirted cleaner through to see if it would help. It didn't.

My gut tells me that if the TPS voltage was correct at idle, it wouldn't hunt, but maybe not.

Thanks kevin

PS 1.5L engine

ezone

As I suspected!
Agreed, wrong.
Honda makes you buy the whole throttle body IF it's even available anymore..



Enter "honda TPS" into Google shopping and start looking. There are probably aftermarket suppliers that will sell it to you.
Then you have to figure out how to replace it? Or have you already figured that out?

TPS needs to be "right" before going further, so solve this problem now.

HTH

atkinson40

Thanks ezone,

I've solved two problems unrelated(maybe) to the hunting problem.

1. The key always got stuck and wouldn't come out. Fix was to adjust the shifter position switch to make it tell the key lock solenoid it was in park. I been battling that for awhile.

2. The shift lock solenoid was made to work by correcting the TPS base idle voltage to around .49V.

I've picked up a couple of the TPS's from the JY and tore one apart, cleaned it up and put it on. Still only gives a voltage from .49V to around 2.3V.

I wasn't able to find the TPS sensor online anywhere. The ones available are all backwards and it doesn't seem that anyone manufactures the correct one. The one available mounts on the opposite side of the TB so it's backwards. I'll check your suggestion for google.

What I'm confused about is why if the ECU sees the correct voltage at idle(.49V) why would the idle still be hosed?

I'm wondering if there is a way to monitor the PW of the secondary(idle) injector to verify that it is the ECU causing the idle to hunt. Is there a way to force the ECU to give a constant PW?

That would at least isolate between the idle injector or a vacuum leak.

I've sprayed carb cleaner every where around the intake manifold and got nothing. Also if it does throw a code(usually 7) the idle settles down. I would expect this if it was the ECU causing the idle injector PW to be varying as the ECU is supposed to fall back to a set PW for the idle injector when it throws a code.

I'm thinking about setting up a resistor voltage divider to set the voltage back to the ECU from the TPS to .49V.

Also a while back I read a service bulletin about the TPS ground not being OK back to the ECU and a fix by taking the ground from the TPS and running it directly to a lug on the IAC. I'm going to undo this. Maybe I read the service bulletin wrong.

Thanks ezone, Kevin

ezone

I don't recall you saying anything about the key/ignition issue, but glad you figured it out.


On the TPS voltage issue, make sure the other 2 wires at the TPS connector have ground and 5 volts. If you don't have a full 5v at the connector, that could explain why the TPS output is so low at wide open throttle position.

I see the bulletin about grounding the TPS and the same bulletin also mentions the shifter position switch issue you had. There are VIN#s for cars affected. May as well try it.

I found one old bulletin about making sure the throttle cable has some slack in it when the throttle is closed: "The EACV has trouble controlling the idle properly if the cable is adjusted too tight."

atkinson40

Thanks ezone.

I undid that service bulletin and it seems to have fixed the idle hunting issue. I just hooked the ground back up to the ECU and it idles sweet. So far. I have my fingers and toes crossed. I been battling that problem for awhile. Maybe my VIN wasn't meant to have the service bulletin.

I may not understand why undoing the service bulletin would fix the hunting issue, but at this point I'll take it with no questions asked and move on. :>) Hopefully

I had 5V and ground at the connector relative to the chassis, but maybe it needed to be 5V and ground relative to the ECU and not the chassis as the service bulletin calls out implementing.

I'd been living with the key issue for so long I forgot about it. I could always finally get the key out, but what a PITA.

I'm hoping this thread is dead. :>)

Thanks ezone, Kevin