Thread: Code 21

I just put a consult cable on the car and checked for codes, I'm getting a code 21 (ignition related). I cleared it out and tried again, just to make sure it wasn't an old stored code, but came right back up. Everything on the car works fine though, nothing out of the ordinary. I checked this with ECUtalk. Any ideas on where to start? :???:

Car has a Bluebird DET, JWT ecu, oem spark plug wires, and I'm running an MSD Digital 6 box.

Code 21 can be triggered from the ignition check signal. Or the condenser is faulty. Basically the ECU is seeing some sort of incorrect voltage from the ignition system. Ive ran across this on my ignition system but remedied it by using capacitors to clean up the signal. I am not sure how to relate this to a CDI system, but with individual inductive coils I just tie the grounds together on secondary and ensure I have a 4.7uf between the power and the ground.

Can you provide a schematic of how your ignition is wired and what coils you are using. Also, how long has this code been on?

I'm still using the stock coil.

I could bypass the box to see if that clears up the problem, but I never noticed a problem when I put it in.

Ok, I see what you did. The msd 6al is just controlling your ignition and the ecu is just sending the signal, correct? So then you have the MSD box powering the coil which would keep the ecu from seeing the ignition check signal which is the negative side of the OEM coil. If its not affecting anything, dont worry about it.

This is the correct way and should eliminate the code. That pin 8 is the ignition check wire, or the coil ground.
http://jimwolftechnology.com/wolfpdf/MSD%20TO%20SR%20240SX.PDF

Correct, plug from the harness goes into MSD box, and output from MSD box goes to coil. But now I'm wondering if that's causing that fault code.

Would this be the same on an external coil setup?

More or less, this is old and is for the distributor with the built in transistor. As you have a 91, the transistor is external and therefore bypassed. The fwd ecu is kinda funny. Where as you dont need this " Ignition Check" in order to have a proper tach reading, however without a tach adapter you will throw a code. Catch 22. But the IGN Check has to see a sine wave that a CDI cannot reproduce, thus the need for the tach adapter.

Got it (sort of)! I'm a dummy when it comes to electrical stuff.

I never got a chance to bypass the MSD and see if that clears the code. I'll get around to it eventually

Look in the FSM. It has steps on how to find the problem your having.

Thanks for the heads up, I'll check it tonight.