No check engine light

[brivers]

Daughter has 97 Altima 4 cylinder. She's been driving it for about 6 months now since I bought and resurected it from a neighbor that had it sitting for about a year and a half. Failed emissions. Codes are P0325 Knock sensor,P0335 crankshaft position sensor, P1336 manufacturers code. They also noted the check engine light does not work. (Probably first time someone has complained about that.) Anyway before spending money for the knock sensor, can I test it with a meter? I'm thinking the knock sensor code is causing the crank sensor code. Has anyone ever heard of the check engine light not working. Doesn't it usually come on when you first turn the key? I guess it could be the bulb but what are the chances of that? She doesn't have a lot of money, so we don't want to waste it on something that won't fix it. Car runs fine. Don't know if this has anything to do with it, but her brakes seam to be going into antilock mode once in a while when braking. Any input would be appreciated. Thanks.

[quick69gto]

PO335 and PO1336 are the same.
PO1336 is Nissans code for the Crankshaft Position Sensor (CKPS)
I would replace that first. If you want to check it, you'll need an ohmmeter to check resistance between the two terminals.
Remove it and the resistance should be between 432-528 Ohms at 77 degrees F.
Once it's replaced, clear all codes from the ECU and drive it for a while. You may have to drive it twice (shut off in between). Re-check for any stored codes.
Yes, the bulb can blow for the check engine light and it should illuminate when the key is in the run position before the car is started. Replace the bulb first.
If the knock sensor code comes back, you can check it using an ohmmeter.
Check resistance between the white wire terminal and ground. Resistance should be 500,000 and 620,000 ohms.
As far as the ABS brakes are concerned, if the ABS light is not on, then the system should be working properly. If the light is on, ABS scanners are manufacturer/model specific so it's not so easy to get the ABS codes from the ABS ECU.
If the ABS light is off, then it's possible that the ABS is going off because of some slick spots on the road or the tires are worn out.
You may have to have the ABS looked at by a pro.
Anyway, good luck!

[brivers]

Thanks for responding. I will check these things out and get back soon with results.