Trouble with TKS circuit on 2006 Regal w/4.3 Mercruiser I/O

[jboozer66]

My "TKS" circuit is not working properly in that after the engine is warm, the fuel enrichment port remains open. I got the schematics (thanks to this forum!) and found only 4 components in the circuit - a 20 A fuse, diode assy, TKS module, and temp sensor. The fuse was blown and blows immediately when replaced. I ohmed out the coil on the TKS module and it checked within specs @ 43 ohms. Temp sensor checks in that it reads below 1 ohm when the engine is warm. The diode reads open in one direction and somewhere between 900 - 1100 ohms in the other. My question is - shouldn't the diode read less than 1 ohm in the "forward biased" direction and if so, is this diode my issue? Any help would be greatly appreciated. Just trying to avoid unnecessary parts swapping.

 

[achris]

Re: Trouble with TKS circuit on 2006 Regal w/4.3 Mercruiser I/O

Diodes shouldn't be measured using the resistance range on your multimeter, use the diode check function. A diode will read open in one direction (cathode to anode) and should should about 0.7 volts drop forward biased (for a silicon rectifier diode, about 0.3v for germanium)...

It sounds more like you have a shorted wire somewhere. Remove the wire immediately before the temperature sensor, if that doesn't blow the fuse, then reconnect it and disconnect at the diode... and work your way along the circuit that way.... Or, meter from the fuse to ground, again disconnecting to find the short....

Chris......

 

[jboozer66]

Re: Trouble with TKS circuit on 2006 Regal w/4.3 Mercruiser I/O

Thanks for the quick response! I should clarify that i did have my meter in "diode check" mode. I heard no chime in the anode to cathode direction but the meter displayed 960. I made an incorrect assumption that that was a resistance reading. Thanks again!

 

[jboozer66]

Re: Trouble with TKS circuit on 2006 Regal w/4.3 Mercruiser I/O

Just thought I'd share what i learned about checking the temp sensor. The sensor in my case was a 2 wire sensor. It checked "OK" in that it was open when the engine was cold and read closed when the engine warmed up. What i also found was that when it was "closed" it was also shorted to ground which was obviously causing the fuse to pop. Thanks again for the advice!