Truck Keeps Throwing Engine Code! Need Help!!!
 

My 99 Dodge Keeps Throwing a engine code. I brought a scanner home from my job and the codes were 1689: No communication between ECM and pump Mod and 1693: ECM Fault. First time the engine light came on it was a cold morning. The truck started for a second then died right out. Engine light came on and stayed on for couple days then went out. It did this a few times after that only when it was really cold. Forgot to say most of the times the truck was plugged in. Now I'm getting a light every couple of days. When I go to start the truck it starts and the idle shoots up to 1500 rpm for a second then back down. Right after it does that I get a check engine light. I just replaced the lift pump a few months ago before putting on the comp box. I also have the bigger banjo fittings installed. I have full gauges and I keep looking at my fuel gauge and it seems to jump up and down to much. At idle it has 12 to 14 psi but when I cruise at light throttle the pressure will drop to 5 psi instantly and then back up. My SPA fuel gauge has a light that I have set at 5psi which comes on when the pressure drops below it. The warning light keeps coming way to often and I don't even have the comp box on.

If anyone could please tell me what those codes mean and why my truck is doing that it would be greatly appreciated!!


Thank You!

First thing I'd check if I ever got the no communication errors is the connections.

Disconnect the ECM connections, clean them, dialectric grease to keep future moisture out, and reconnect.
Same thing with all the Comp connections, and pump connections.
Wouldn't hurt to also do the PCM connections as well.


phox

I took the ECM connection off last week and cleaned it but still threw the code. I will try to clean the other connections tommorow. Thank you for the reply!

Not totally familiar with the "comp box" but doesn't it splice into the injector pump wire? You may remove it and see if the prob continues.

My lift pump died the same way that you are describing. You would be cruising along and it would be around 13 PSI and if you would put a load on it then all of a sudden it would drop down to 3 or 4 PSI ans would not come back up until you shut the truck off and restarted. I ended up replacing the lift pump again and all was well again. That lift pump was only 5 months old by the way.

Hope you get it figured out.


Jason

Thanks for all the help!!!! I cleaned all the connections and put dialectric grease on all of them. So far no code and it seemed to run a little better. My lift pump at idle is 12 psi but I'm driving down the road at part throttle it will drop to below 5 psi and then come back up alot. My warning light on my fuel gauge which is set at 5psi seems to be flashing alot!!. First thing I'm going to do is check my fuel gauge and make sure that it is accurate. If it is I not even going to bother with another lift pump. I'll put a bigger inline pump so I don't have to worry cause I going to do alot of work to the motor as soon as I get the tranny upgrades from DTT in my truck. Thanks for the replies and I'll keep you posted..



Rich


99 2500 Quad cab,edge comp,dd1's,4 inch exhaust(muffler MIA)SPA digital Gauges,AFE Mega Cannon