Another 1689 dtc question

[dave110]

Hello. I was wondering if anybody can answer me this one just to satisfy my curiosity. Theres a guy over on CF who's Raptor 100 quit due to dirt in the gears. He got a P0230 which makes sense and also a p1689 code. How can lift pump trouble cause a 1689? The last time I got one the VP was done. What really baffles me is he said once the lift pump was fixed it cleared all the codes. What am I missing?

[Mopar1973Man]

Here is the diagnostics for the P1689 code... http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/228-p1689-no-communication-between-ecm-and-vp44 But typically the fuel flow stops or slows to point he the pressure falls below 14 PSI the overflow valve starts closing and the cooling fuel disappears so now the computer on the VP44 (FPCM Fuel Pump Control Module) start losing its cooling fuel and the electronics starting getting hot. Yes. I know there is a P0168 code for over temp but in all these years I've never seen 1 report of it. http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/155-p0168-decreased-engine-performance-due-to-high-injection-pump-fuel-temperature I consider the P0168 code worthless because you'll never see it.

[dave110]

Thanks,I knew I could get an answer here!. So bad LP/no fuel flow could overheat the IP, stop it from working until it cools down, and set the code, and then be OK again after fuel flow is restored?

[Mopar1973Man]

Maybe or maybe not... Depends on how hot the electronics might of gotten. It might be other things too.

[h=2]Possible Causes[/h]

[*] Wiring & Connectors

[*] Fuel Injection Pump Relay Output Circuit Open

[*] Ground Circuit Open Or High Resistance

[*] Datalink (+) Circuit Open

[*] Datalink (+) Circuit Shorted To Ground

[*] Datalink (-) Open

[*] Datalink (-) Shorted To Ground

[*] ECM