Code 23, CAS wiring problem

[alex99gst]

I'm really close to finishing up my 2.4L project and the other day when I tried to start the car nothing would happen. Replaced the MPI fuse, coil pack, and transistor and then it would try to start. The car will start for a couple seconds, throw the code 23 (TDC Sensor, vfaq said CAS) and then die. I just swapped a working CAS on and nothing changed. I tested the wiring and I couldn't get anything from terminals 3 and 1 (the 12v and 5ish sources). I've pulled out the harness to try to track down why I can't get any power. Does anyone have any ideas? This all worked a couple months ago with the old engine in. Thanks

 

[yokotabrat]

Does the ecu check engine light come on for 5 seconds when you first turn the key to the ON position? Is this on a 1g or 2g you're working on? Are you measuring from ground to Pin 3 on the CAS and not seeing 12V when the key is in the ON position?

 

[alex99gst]

If I clear the CEL then nothing happens when the key is turned to on. With the key "on" there is no signal at all from the ground to pin 3 or pin 1. This is on my 1g.

 

[yokotabrat]

Since you're seeing a CEL and able to see it's for the CAS, the ecu is powered up. No 12V at the CAS indicates a possible wiring problem since the MPI relay has been activated because the ecu has power. Power from the MPI relay goes to a bunch of different sensors, so it sounds like you might need to do some tracing of the red power wire going to the CAS from the MPI relay near the ecu.

Really quick first, I just want to make sure you're measuring pin 3 as being the red wire on the CAS harness? Are you doing this with the CAS unplugged? Also, with the CAS unplugged, pins 1 and 2 (black and white wires) should read 5V with the key in the on position. Is there anything tapped into pin 1 like a MAFT?

 

[alex99gst]

Yeah, I am measuring the red wire with it unplugged. I can't get a reading on any of the wires. Nothing is tapped into any of the wires. Thanks for your help man. I'll work on tracking it down today.

 

[alex99gst]

So I go outside and turn the key to the on position and I hear a loud ticking noise coming from the center console. I pulled the ECU and it seems like I have a tiny leak from a capacitor. I've never seen what it looks like, but some of the electrical stuff looks damaged. I'm going to try to contact steve about ECU repair. Do you think that would be the problem?

 

[yokotabrat]

The leaky caps will definitely cause the ticking under the dash. That's usually the mpi relay. The ecu controls the activation of the mpi relay by pulling a couple of pins low. If the mpi relay doesn't get activated the ecu has no power and neither do any of the sensors like the CAS. The easy way to tell if the mpi relay is not activated and the ecu has no power is if there is no CEL on during the first 5 seconds of turning the key to "ON" and the boost gauge will not be at 0.

If the board has leaky caps definitely send it in to get repaired. It already sounds like it's done some damage and will just get worse with time. Be aware though, it may end up being cheaper to get a new ecu than get it repaired depending on the damage already done. Unless that is you have an eprom ecu. Hope this helps.

 

[alex99gst]

Thanks, I have an eprom and from the looks of it, the capacitor didn't leak much at all and barely damaged 2 small things on the ECU. I'm going to go ahead and get it socketed and repaired since I assume the repairs are mostly minor. I'll get pictures up ASAP once I get my camera back tonight.