Here's the deal- Beginning this winter, when I turn the key to the "on" position, there is no wait to start light and no relay click going on. After leaving the key in the "on" postion for about 30 seconds or so, a very quiet clicking from the small relay mounted on the inner fender (not the actual heated air intake relays) begins. This clicking starts off very quick and lasts for about a minute or so getting louder all the time and slowing down slightly. During the clicking the "wait to start" and "water in fuel" lights are blinking together. Eventually the clicking stops, the air intake heater relays let off their loud click about 3 times (the wait to start light then stops blinking and stays on constant) and the intake heater gets solid power for about 10 seconds before everything shuts off. The intake air temp sensor has been replaced and is working, the relay that initially does the clicking has been replaced, all of the associated wires from the PCM harness have been tested for continuity, the heater itself has been removed and tested, all grounds for the components have been traced and are solid. Obviously, the 10 seconds or so that the intake heater actually gets power isn' t enough to heat anything up enough to matter. Has anyone else ever ran into this? How many people side with my idea that everything is being caused by a faulty PCM?

 

P.S. ---the vehicle is a 92 D350, unmodified

 

[quote author=gsondag link=board=13;threadid=23985;start=0#msg226276 date=1071820429] How many people side with my idea that everything is being caused by a faulty PCM?
[/quote]I do.
Best deal I've found is on rebuilt PCMs from Napa.

 

gsondag,

I had a 91.5 for 140,000 miles and the heater grids are hardly an issue on that engine. the truck starts so good cold that I never really understood why they came with the grids. Even with temps in the teens the grids cycling did not seem to eliminate smoke after start up nor did they noticably aid in the startup. I did go through two of the heat sensor switches that advances the timing when cold. If if fails it will smoke quite a bit when cold. Otherwise the truck always started cold about as good as when warm, almost immediately. I always figured the grids were for start ups colder than minus 10 or 20 degrees F. For those temps, of course, there is the block heater. Good luck in tracking it down.

 

Hmmm..something is definetly amuck, and like you say, could be your PCM if that is what ultimately controls the cycling of the heater grids. My set up seems to be working great, depending on the temp, will cycle accordingly up to a couple of minutes. ( Gets cold up here ).

 

My Haynes book for '94 and up has excellent step-by-step instructions for checking the whole grid heater system. I don't know how the first gen book is but it might be worth a look.

 

Do yourself a favor and go to www.techauthority.com and order the right book for the truck. The older ones are $70 plus shipping. I just bought one for my sons 94 last week and just ordered one for my Neon last night. The newer ones are $90.
You will use it more than once, I gaurentee.

 

If I'm not mistaken Dodge factory service manuals are no longer available pre '94.