Engine/Transmission (1998.5 - 2002) Question about PCM/ECM Truck dies for no reason... p 1693

[TPlasek]

I recently replaced my VP44 thinking it was bad. I have good fuel pressure at the VP44 and the lift pump is functioning correctly.



The truck ran great for 2 days after I installed the new VP44 and now it is hard to start again. It also decides to die whenever it wants to going down the road.



So, it is not lift pump, not fuel pressure, not the VP44, what else could it be??? Do the Pump control modules go out??? If someone has had one go out, what were the symptoms. This problem is driving me nuts as well as making me poor. At least now I think I have a perfectly good working VP44 as a backup. Now if I could only get my truck to run and start I would be in great shape.



Could this be a ECM/PCM problem. Anytime it happens I get a P1693, which doesn't mean much to me...

 

[ToolManTimTaylor]

1693 Companion code? No other codes are present positive?

Does the Tach dance arround at all? Does the Idle Lope Bad when it idles?

Cam position / Crank sensor issue?

 

[TPlasek]

the tach only moves around 50rpms up and down, and that is only if the A/C compressor is on. If not, it is rock steady. It has absolutly NO symprtoms. It does it when it want to without warning. It used to just be hard to start, but now it dies. It either starts normally or doesn't. There doesn't seems to be anything I can do to change that. It never misses stumbles ect. It also either starts normally with no hickups or it doesn't start at all. Walk away come back in 15 minutes and it will start...

 

[ToolManTimTaylor]

Sounds stupid but how's the filter's condition? It could be clogged with gelled diesel or something and when the truck runs it just is emptying the filter housing? that would show good pressures but bleed down as she runs.

 

[ToolManTimTaylor]

Forgot to ask how cold does it get in that part of Texas? This could be a true scenereo. Have you used any treatments? All connections on the VP44 good cause I know you were in there.

 

[TPlasek]

It gets into the low 50's at night. It will do it when it is warm, cold, morning, day, evening. It seems to be most prominant, if I have already driven it somewhere and I come out to restart... I think I have tried everything. I have unplugged and replugged every connector I could find. Including: VP44, connectors behind air box, IAT, MAP, EZ unplugged or plugged in doesn't matter, lift pump, the large connector with the white lock clip. I just can't seem to shake this problem. It seems like there is no connector I can wiggle to make it start(when it fails). I just have to walk away and come back in 15 minutes. It usually starts then.

 

[ToolManTimTaylor]

A couple more suggestions before I run out. Other than Checking the Obvious Filter , VP44 Fuel connections , Water Drain valve , ETC.



Take a look at the Battery terminals for a good connection as well as the Grounding strap. Iv'e seen a truck do this and sure enough a slightly corroded connection won't send proper voltage to the certain circuts and sending units / solonoids that require a pre determined voltage. We all know the cummins as of now is an electrical jungle under the hood.

 

[Turbo Tim 1]

My truck just did this tonight, I was pulling in to the grocery store and waiting for some people to cross the road and she quit. I had just filled up with fuel so I figured great I got a bad load of fuel. I checked the codes and saw p1693 and nothing else, tried cranking it but it just cranked. I waited a minute and tried again and it started up fine and seems to run perfect, all indications are normal. Any ideas other than whats already been said?

 

[TPlasek]

I have not actually changed the fuel filter. Since I do have a gauge hooked up at the VP44, I figured as long as I was getting a min of 10psi during all running conditions and 7 during cranking I was OK. When I get home, I will install a new filter, just in case. I have however, lifted the drian valve and shut it many times while I was troubleshooting. Never saw water.



I haven’t thought of the actual battery wires nor accessory wires that run to the fuse/power distribution boxes. I will check these tonight as well. Maybe I can clamp on an extra ground clamp from battery to the ecm body or the pcm body. See if the problem goes away.



I heard somewhere you can check for 12volts at the vp44 on 2 pins. I'm not sure which two. I heard if there was power on these two pins, the truck should start and idle as long as the VP44 is NOT bad. I have a hard time believing that I have two Vp44's with identical problems, but if anyone knows which two pins I should check please let me know.



Thanks for the tips,

Keep them coming...



edit ps. Mine has done it on numerous tanks of fuel for the past three months.

 

[kaffine krazed]

Have you tried changing the relay for the VP-44? Just swap it with another relay you know works like AC or starter.



Pin 7 is 12 volt and pin 6 is ground at the injection pump. The only problem with checking for voltage by disconnecting the VP-44 is you wont find out if there is high resistane in the circuit that way. If you can measure the voltage with the engine running or prefferably leave a voltmeter connected and when the truck dies. Another way is to hook a load up like a headlight to the VP-44 connector and make sure it glows brightly for 20 seconds.

 

[TPlasek]

That is GREAT thinking on that relay, I would have never thought about that one. I hope it is the relay in the lower left corner of the box, if standing on the side of the truck. It is labeled fuel system relay. I figured it was for the lift pump, but the lift pump will run with it unplugged. Funny thing is when I unplugged it with the key on, I another P1693 code, if that means anything. This is the same code I get when it acts up.



Today, I installed a new fuel filter, as well as cleaned all the connections I could find. I cleaned all the battery connectors, and all the ground straps that I could find. I also (before I was told about the relay) took all the fuses out and checked them. I also sprayed contact cleaner where all the fuses go and worked the fuses in and out a few times each incase there was corrosion there. It has not acted up this evening, after I completed all the above.



I am going to wait on the relay. I want to see if I may have fixed the problem already. As soon as it acts up, I will switch relays. If it doesn't act up in the next few days, I'll switch or replace it anyways. It could still be bad and “undervoltaging” the VP44 plus whatever else it supports. Even if it is good, it will make feel better by installing/switching a new one.



Thanks so much for all your help, I'll let you know if it is really fixed or not in the next day or two. I am keeping my fingers crossed but, as of now, I am not sure if it is really fixed.



I especially like that relay info. I think that could be a good candidate for the problem. I wish I would have thought of that before I purchased a new VP44.

 

[Big White Beast]

Just a thought.........

I was browsing through the TSB's and there was one under the 2001's for trucks that were hard starting at temperature with winter blend fuels. It involved a reflash.



Doesn't account for the code though. Those relay's aren't much, I would replace it just to be on the safe side.



Garrett

 

[Turbo Tim 1]

Mine acted up again today, it didn't quit but was running rough at idle and if you hit the go pedal it would still cut in and out. I shut it down checked for new codes but there weren't any. Restarted it and it was running fine, other than the check engine light is on again. I removed the battery terminals on the passenger side battery and cleaned them but still have to do the drivers side and then check the ground strap. First I need to get the truck un-frozen a little and dried out.

 

[TPlasek]

I guess cleaning the connections and the fuses didn't help. I came out today and the truck wouldn't start.



I know for sure it is something electrical. When you turn the key to the ign ON position, you can hear the VP44 clicking on and off rapidly for about 3 to 5 seconds. I can get someone to turn the key while I am under the hood and it is definably the VP44 (new one).



I exchanged the fuel system relay with a new one. The VP44 then only made one click when I turned the key on and it started right up. When I got to work, I cycled the key a few times and I could get maybe a couple of clicks out of it. I think the new relay may just be a band aid for the real problem.



Does anyone think that I could have bad contacts in the actual ign switch. Could the ign switch not be giving enough power to energize the relay? I think I will try to engage the relay manually with a wire off the battery. If it is not this, I think it has to be the computer that the VP 44 plugs into.

 

[Turbo Tim 1]

I possibly have found the problem in mine! A guy in a chevy gasser was trying to impress me today so I went to bump up my comp to level 5 and it wouldn't move off of level two. When I got to where I was going I picked up the comp (it is in the ash tray) and the truck quit. I was wiggling it around and the truck stumbled again, seem like something inside the comp has gone kaput. I can't turn it off or change the levels. I'll keep you posted

 

[kaffine krazed]

Looking at a wiring diagram for a 2000 the fuel system relay is power side controled through the ECM pin 36 BR/WT wire and gets it's ground through joint connector #1 in the pdc and the G102. The power side of the relay is feed from Batt A0 through fuse #3 (20A) through joint connector #2 in the PDC RD/WT pin 30 on the relay. From the relay pin 87 RD/LG through C130 pin 5 to C125 pin 7 to fuel injection pump pin 7. The ignition switch is not part of the circuit except that it powers up the ECM which controls the power to the control side of the relay.



The code P1693 will set anytime there is a code in the ECM .



You could make some jumper wires to allow the relay to be remotely mounted to allow for hooking up a volt meter to verify correct voltages and check for voltage drops.



You might want to try and take your truck to an autozone. I know they are offering to read the codes but I'm not sure if they can read the codes in the ECM and or any code other than a P0xxx code they should also be able to clear the codes so you can see if the reset.

 

[TPlasek]

Thanks for the info. . Guess that rules out the ignition switch. I am still going strong since I replaced the Fuel System Relay. I have had no problems starting my truck.



I think if the problem should arise again, it will probably turn out to be the ECM. I'll check the voltages and grounds to the relay before I Buy an ECM.



Thanks once again.

 

[Turbo Tim 1]

TPlasek,



Anymore trouble with your truck? Mine was definantly the fueling box, I've had it removed since Friday last week and haven't had any troubles other than the truck really feels like a dog now:{ You might try disconnecting your box if you are still having troubles.



Good luck



Tim

 

[TPlasek]

The first thing I did was unplug the EZ. It made no difference. I have not had a single hint of a problem since I changed the relay. Just wished I tried that before I purchased the new pump.



The new pump doesn't seem to have the same off idle power as the old pump.