code 56: corrosive coolant

[rockcrawl]

Looking for info on the cause of a code 56, corrosive coolant. The engine was just installed (Fiero) and I got a code 56 after the first test drive. This is a '91-93 system. Coolant is new. What tells the ECM that the coolant is corrosive. I assume it's monitoring the conductance somehow, but I don't see how. Anyone here have a FSM with code tips?

[brian89gp]

First, there is a corrosivity/low level sensor that is located in the radiator but it is only hooked up to the low coolant light, not the ECM.

Second, I have code 56 as a QDM B fault. By chance are you using an auto chip with a manual or non-electric auto tranny?

[Lyle's GTP]

OK guy's I'm adding in here, sorry "rockcrawl". I can't get this low coolant dummy light to quite coming on. It's been on for like a year, it used to be on then off, then it was just on. When it first started, it would come on when my car was cold and then go out when it warmed up.

This weekend, I pulled the sensor and cleaned it out, as per my instructions from you guys. The sensor was very gummed up, so I cleaned out all the gunk then used some steel wool to clean the sedement from the eloctrode. I the filled the car with new coolant and a new rad cap. I fired the bitch up and low and behold there was no light. WOOHOO!!!!! However, the next time I drove it the fucking light is back on again. Then after driving it, it went out after it warmed up. So, I bled the system for air again, then added a little more coolant (just to top up the tank). There was no change, the light stayed on until the car warmed up again. I have driven the car 3 more times since then and the fucking, god damn light is still on. Also, the car came up to temp on all three drives. Fucking, fuck-fuck, fucker, fuckaroo!!!!!!! I'm getting pissed. Maybe a bad sensor, wiring, air bubble in my rad, what? Help...........please.

Lyle

[RednBlack]

Have you bought a new sensor yet? Just curious.

[Lyle's GTP]

No, not yet. I want to make sure this one is fucked first. Cause GM wants $60.00 for the POS and they kinda have a "no-return" policy on used sensors.

Lyle

[RednBlack]

If your light works and the wiring has not been f.....d with. Sounds like you have a bad or semi-bad sensor. Get one from a junker. See if symptoms are exactly the same. If they are not, then spend a few bucks and get a new one. At least you have alleviated that problem. I'm sure there is a way to test the sensor, I just don't know what it is.