Archived p 1693 code

[RCondron]

I have a 01 3500. I haven't used the truck much since I got a 05 shop truck. we had a new inj. pump installed when the lift pump went out. It worked for 1 week then the code came back and would not start, they repaced it again and it never did start every time since then but it would start after trying 3 to 8 times. the truck runs great but it is getting less reliable about starting and I am going on vacation soon. Is there any thing else that will trigger the code? the pump was changed 3 times, the computer was changed, and the Dodge rep was out and reflashed the computer twice. All this was about 3 years ago.

 

[JLandry]

That P1693 DTC (Diagnostic Trouble Code) simply means the ECM had detected a DTC in the PCM (Powertrain Control Module). You need to use a code scanner to check what the DTC in the PCM is (was), write the codes down, and then erase both.



If you have a DTC code set in the PCM, let us know what it is and maybe we can better narrow down the root cause of the problem.



Hard starting can be caused by many things. You didn't indicate whether the truck has exhaust smoke when starting. Here's an excerpt from the Powertrain Diagnostic Manual:

Symptom: ENGINE DIFFICULT TO START OR WILL NOT START (NO EXHAUST SMOKE WHILE CRANKING)



This is a list of possible causes:



Check for any TSBs for ECM calibration updates that my apply.

Fuel level low.

Poor quality or improper grade of fuel.

Fuel filter plugged.

Fuel tank venting.

Low fuel pressure.

Air in fuel system

Fuel Lift Pump malfunctioning.

Fuel Inlet restriction.

Fuel injection pump supply voltage open or low voltage.

Fuel injection pump static timing.

Fuel inlet line kinked or restricted.

Fuel return passage or fuel return line kinked or restricted.

Injectors are incorrect.

Injector shim thickness is incorrect.

Injector malfunction.

Fuel connector leaking fuel.

Engine Speed sensor (ESS) and/or circuit malfunction.

Moisture in harness connectors or corroded terminals.

Skim issues.

Battery voltage low.

Ignition switch supply voltage low or open.

Battery voltage to ECM is low or open.

Electrical noise.

Fuel injection pump.

Engine Control Module.

Internal engine damage.​

 

[RCondron]

I'll see if I can get a scanner and check the codes. what ever it is the dealer didnt find the problem. most items on the list have been checked and are ok. supply voltages have not been checked out or fuel return lines.

 

[JLandry]

RCondron,



Some of these may seem like dumb questions, but I need to clarify things and rule some things out...



1. Did the truck start properly *before* the 1st injection pump and lift pump were installed? In other words, prior to installing a new lift pump and fuel injection pump, you never had a starting problem... correct?



2. Why did the lift pump and fuel injection pump need to be replaced the first time? Specifically, how did you know one (or both) were bad? Exactly what happened?



3. Was *anything* else done to the truck when the lift pump and fuel injection pump were replaced that first time?



4. You said: "... they repaced it again and it never did start every time since then... " Does this mean a 2nd injection pump was installed to try and correct the hard starting problem, but nothing else was replaced at that time?



5. You also said: "... the pump was changed 3 times... " Does this mean the fuel injection pump has been replaced 3 times, or the lift pump has been replaced 3 times?



6. How many times has the lift pump been replaced since the hard starting problem began?



7. Has anyone tested and verified the lift pump is operating at the correct times, producing proper fuel pressures, and providing adequate fuel volume?



8. What are the fuel pressure readings at idle, cruise, and WOT (Wide Open Throttle).



9. Has the fuel filter been replaced?



10. Has the inlet screen in the tank been cleaned?



11. You said: "... the computer was changed... " Are we talking about the ECM (Engine Control Module) or the PCM (Powertrain Control Module)? Was this item replaced in order to try and solve the hard starting problem, or was it chnaged before the problem started?



Undoubtedly more questions will follow to hopefully home in on a cause. I do have some ideas.



Best regards,



John L.

 

[RCondron]

John thanks for the info here are answers to the questions.

#1 yes

#2 I lost fuel pressure and got to my shop and replaced it that night and the truck ran fine for a few weeks and the the code and light came on and wouldn't start after that

#3 no

#4 yes

#5 the inj. pump

#6 once I put on a Fass pump.

#7 the lift pump comes on most of the tim whe the key is turned on but not all the time. when the engine is bumped over the pump runs for 20-25 sec. The pressure is 18-20psi but I don't know the volume. the truck runs fine when it starts and the engine pulls great with a load (16,000 lb trailer) at 6,000 ft ele. with 8-10 fuel press. at WOT.

#8 idle 18-20

cruise 12-15

WOT 10-12

#9 the filter has been replaced but not in the past 1 1/2 years (2,200 miles)

#10 no

#11 I'm not sure but I think the ECM but the old one was put back on when it did not correct the no start problem. It was changed when the Dodge rep. came out to find the problem along with the 3rd inj. pump. Thats when he said the couldn't warranty the problem any more.



After every thing was changed and played with the truck would start 75% of the time but when it wouldn't you would have to try 3 to 10 or more times before it would start. and it is progressively getting worse no it starts only 30-40% of the time but it has never totally failed me.

 

[Missouri Mule]

Seems like air getting into system or electronic problem.

 

[JLandry]

RCondron,



With all that's been done, it seems you should be able to safely rule out the VP44 injection pump, the lift pump, the ECM itself, the ECM grounding, and ECM connector as being culprits.



Does the engine crank at normal speed?



Does the engine start normally (right away) after it's been run awhile? If yes, how long does it typically have to sit before the difficult start comes back?



Have you tried replacing the Crank Angle Position Sensor or the IAT (Intake Air Temp) sensor?



Another thing to try is to swap out the relay that controls the VP44 injection pump. It's in the PDC (Power Dist. Center) which is under the hood on the driver's fender. The relay is marked "FUEL PUMP. " Just swap it with another more non-essential relay (wipers) located in the PDC and see if that makes any difference.



You might also take the time to remove the cap from the fuel filter cannister and carefully examine, clean, and lubricate the o-ring seal before screwing the cap back on. There have been reports of air entering the fuel filter cannister and causing starting problems due to a simple tweaked o-ring under the cap. Personally I'd go ahead and replace the fuel filter again if you open the cannister. It certainly can't hurt and they aren't too expensive.



And it would still be worthwhile to buy a code scanner and check for DTC's just to make sure there aren't any. Some auto parts stores will check for codes for free also, but having a code scanner handy is always good.



John L.

 

[RCondron]

JLandry

the engine cranks normally all the time.

the engine starts sometimes right away after running and sometimes not (like when you shut down for the fast food orders and then start up again). When cold it sometime starts first time other times not. It is not consistant enough to get a good handle on the problem.

I reeplaced the crank sensorlast year when I checked out all the elec. connectors and found it loose, I tightened it up, no differance and replaced it anyway.

I haven't replace the IAT.

I know the problem is more likely electical by the way the engine runs. I'll swap out the relay and try again. After your first reply I checked all the contacts in the PDC,sprayed them and blew it out, and they all looked clean. I tried it again but still no luck. sometimes starting sometimes not. I carry a spare filter and will change it out this weekend. I'll change it out this weekend. I'm busy this week getting a party going for WWII vets this Sat. moving some tanks and artillery at our museum. I'll get back to you Mon.



thanks Roger

 

[JLandry]

the engine cranks normally all the time.

So that would eliminate low battery voltage as a possibility.

the engine starts sometimes right away after running and sometimes not (like when you shut down for the fast food orders and then start up again). When cold it sometime starts first time other times not. It is not consistant enough to get a good handle on the problem.

That's frustrating. I was hoping you could relate the problem to a period of time the engine sits idle or a temperature.

I haven't replace the IAT.

The IAT would be a long-shot for sure, but they're cheap and can't hurt to change. Keep the old one as a spare if the new one doesn't help.

I know the problem is more likely electical by the way the engine runs.

At this point I tend to agree with you.



My thought about the relay was that if the contacts within weren't making good consistent connections, then the VP44 would be getting slightly low supply voltage at times. When it did get good voltage, of course it would start fine and the engine would run fine. It was also a long shot.

I carry a spare filter and will change it out this weekend. I'll change it out this weekend. I'm busy this week getting a party going for WWII vets this Sat. moving some tanks and artillery at our museum. I'll get back to you Mon.

Good. In the mean time I'll research this some more. I'll take a look at the wiring diagrams to see if I can come up with some other electric scenarios where the engine would crank normally but not allow the VP44 to inject fuel into the cylinders... like maybe a worn ignition switch?



Have fun with those tanks.



John L.

 

[JLandry]

Roger,



Did you ever get a code scanner or go to an auto parts store to see if a DTC is currently set in the PCM? Just curious. A DTC might help us narrow down the cause of this problem.



Anyway, I did some reading this afternoon in the Dodge service manual and powertrain diagnostic manuals to see if I could come up with any more ideas. Here's a new one...



Try swapping out the relay in the PDC labeled: "ASD" (which stands for Auto Shutdown Relay) with a known good relay and see if that makes any difference.



If that doesn't work, then it might not hurt to check the power and ground connections of the PDC and ECM. I can give you the exact connector pins to check if you want to try that.



I'm still thinking...



Good luck,



John L.

 

[RCondron]

Jlandry, I replaced the fuel filter sunday and no luck. I went to the dealer and got a new relay on monday and replaced the ASD relay and I nearly ran down the batteries starting it and it never once did not start ( about 30 times in 15 min. ) I'm not sure how it funtions in the circuit but it worked so far. I'll drive it for the next week and give it a go. Thanks for all your help, I never would of thought of replacing that relay.



Roger

 

[JLandry]

... it never once did not start ( about 30 times in 15 min. )

Wow! That's great news Roger!



From what I can tell in looking at the schematics, the ASD circuit is what the PCM uses to enable the engine to run. Here's how I think it works...



When the ignition key is turned to the run position, the ASD relay is energized, which provides a run signal to the PCM. The PCM then tells the ECM to allow the fuel injection system to operate. When the ignition key is turned off, the ASD de-energizes, and the PCM sends a signal to the ECM to stop the fuel injection system so the engine stops running.



Keep us posted on how it holds up over the long term.



Best regards,



John L.