I recently picked up a 98' Civic DX Hatchback AT from a friend. Its currently in limp mode and when I check the code it pops a code 4, Crank Position Sensor. He has replaced the dizzy already and I can confirm the CKP is okay as I've checked resistance at the dizzy connector and the pins 2 and 6 have ~400ohms (spec is 250-700 ohms according to a search).

Now I'm abit stumped. I've checked for continuity from the ecu connector to the dizzy connector but its odd. When I go from pin C12 (white wire) to pin 6 (white wire) at the dizzy I get nothing, but if I go from pin C12 (white wire) at the ecu to pin 2 (blue wire) at the dizzy, my meter beeps like there is continuity. Now going from pin C2 (blue wire) at the ecu to either pin 2 (blue wire) or pin 6 (white wire) at the dizzy I get nothing.

To me I dont understand why I'm getting a beep going from the white wire at the ecu to the blue wire at the dizzy connector. I'm really not sure what to do from here, it's probably something simple but I'm just alittle frustrated/confused.

Any help is appreciated.

 

How are you doing the continuity tests? What are you touching with each meter probe? What is unplugged and plugged in the CKP circuit when you are doing the tests? Post pictures of ECU terminals C2 and C12 and distributor terminals 2 and 6 that you are testing.

 

When doing the testing I unplugged the distributor connector. I put 1 probe into the ecu connector at C12 (white wire) and 1 probe at the distributor terminal (female/harness side) pin 2 (blue wire) and my meter beeps like there is continuity. That is the only time I'm getting continuity, I've tried C12 and pin 6, C2 and pin 6, C2 and pin 2 with none of them seeing continuity.

For testing the CKP I probed male/dizzy side pin 2 to pin 6 and got ~400 ohms.

I also opened the wiring harness where it goes into the cabin, below the battery, and was looking for the darker blue (ie: not light blue) wire thinking maybe it had rubbed a short or something but I do not even see a blue wire in the main harness.

I can see about snapping some pictures shortly.

 

Test for continuity to body ground (short) at C12 and pin 2 individually.

 

No continuity to ground at either pin 2 nor C12, also for giggles/grins I checked for continuity to ground at pin 6 and C2, neither had continuity there either.


Here are the pictures of the connectors.

http://imageshack.us/g/262/006ohb.jpg/

 

Here's what your tests show:



The upper pair of wires show how the circuit should be. The lower pair of wires show how the circuit is. It appears that somewhere between the ECU and distributor the white wire from C12 and blue wire pin 2 are cut and spliced together, whereas the blue wire from C2 and the white wire from pin 6 are just cut and connected to nothing. Either run new white and blue wires or locate the cut and splice and repair it.

 

That's definitely what it appears to be. I'll see about running new wires tomorrow. Any recommendations on wire size?

Thanks a ton for the help, I'll update the thread after I get some wires run and hopefully have a car that's finally out of limp mode!

 

Just match the gauge of the stock wires.

 

Sorry if im intruding, im new to this site. But where do i go if i want to post something? Need some advice on my Halos that i just installed yesterday.... they work just fine, its just there not very bright like they were on the advertisement.

 

or a personal message would help. once again, sorry if im intruding.

 

Alright, so I ran 2 new wires and spliced them in. I'm now getting continuity at the ecu pins from the dizzy terminal. But I'm still popping code 4 nearly immediately after I start the car up. I'm kind of at a loss now as I thought (hoped) fixing the wiring would have been what I needed.

From here though, it almost has to be ECU? I mean I did the ohm test on the CKP and it was within specs, now I have the wiring working right with continuity from ecu connector to dizzy terminal.

 

Did you reset the ECU after the wire repair?

Ohm test the CKP sensor from the ECU connector terminals and also check for a short at each wire.

 

I did reset the ECU a couple times (pulled 7.5a "backup radio" fuse). When I go to start the car after ECU resets it has to spin over a couple times before it will start, then once it starts the CEL pops on about 3sec later.

I checked the resistance at the ECU connector and get ~388 ohms which suggests its going through the CKP sensor correctly.

 

If there's no short, next swap in a known good ECU.

 

Hey yea I checked for shorts and didnt come up with anything.

I cant seem to find a local ECU so I'm ordering one, hopefully it will be here by the end of next week. With any luck I'll have a good running car next weekend! (crosses fingers)

I'll update whenever the ECU arrives. Thanks again for your help.

 

Alright, new ECU came into today. Popped it in, car is still running bad in limp mode with code 4 only. Any ideas?

I checked the resistance of the CKP sensor again and its within range. No shorts to ground can be found. Kind of at a loss here.

 

Check the two wires for an open.

 

All of the wiring appears to be fine, no opens.

 

The possibilities are the two wires, the distributor, or the ECU. That's about it.

 

Thats exactly what I was thinking.. and afraid of. lol.

Well I guess its time to price out a distributor for this beast.

Thanks again for all your help, I'll again update this thread once I'm able to source a distributor.

 

A problem with the distributor should be revealed by resistance and short tests of the two distributor CKP wires.

 

Yea, I've poked and poked but cannot find any wiring problems now. The resistance is ~375-380 range for the sensor which is very close to the bottom end of spec for it (350-700ohms). Could it be that because it is so close to the lower limit that its popping it for low signal?

*edit* I've also been following a diagnostics sheet I got from a friend who works for a Honda dealer in TX (his name is Ron too, lol). Thats where I got the spec of 350-700ohms

 

This is speculation on my part, by I think your tests are missing a wire problem.

-Have you tested resistance between C2 and C12 with the distributor plugged in?
-Have you tested for a short from C2 and C12 individually with the distributor plugged in?

 

Yes and I just went out to triple check.

Resistance from C2 to C12 with dizzy plugged in was ~390-400 range

Was no continuity to ground on either C2 or C12