Howdy FTE,

So for what seems like my millionth post on wont start, my truck again won't start. What I've done or had done: replaced main wiring harness, replaced 8 glow plugs, replaced 2 injectors, replaced block heater, replaced GPR, switched to synthetic oil, fuel filter change x2, replaced CPS (2x- both gray), replaced valve cover harness. Pretty much after each "change" the truck will start and run great for a day with lots of off/on. After it sits overnight and cools off it will not start the next morning. Today after it wouldn't start, I check the HPOP res and it was low (1st time it was low), so I filled it up to about 1/2" below, and still no start. I also disconnected the batts, let it sit and reconnected. Thurs when I had it towed to the shop to have the wiring harness replaced (the insulation was falling off all over the place - the wires going into the valve cover connection were bare) the checked codes, and I had quite a few. Fri, after they replaced the harness no codes. When I tried to start it today - no codes (I borrowed a small OBD code reader form the shop). WTS light comes on, oil pressure reads after about 10 sec of cranking (1st time, then after about 2 sec on future cranks), a few hundred RPM when cranking. Truck turns over great, but no smoke, no fuel smell, and no boom.

HELP!!

 

So they put a new uvc harness in the other day?

 

How many other wiring harnesses are in the same condition? Make sure the wires going to the IPR are not in the same condition.

If they replaced the wires going to the VC, how much wiring was replaced? Did they check the pass thru connector on the VC gasket to make sure the shorts did not burn one or more of the pins?

 

The replaced the main harness the $650 one that has a bunch of connections on it, both valve covers, alternator, GPR, IPR, etc. An an not sure about if they checked the internal pins of the VC gastet, but the truck fired up as soon as they replaced it. It then ran for the rest of the day for me just fine. I started and stopped quite a few times, and it sit through dinner, but never cooled down on the way.

 

I'm not familiar with a $650 harness, so I really don't know how far it goes. Did they stop at the square box on the drivers valve cover, or continue all the way to the IDM?

I'll assume you've been keeping the batteries on a charger so the voltage doesn't drop too low from trying to start it. Try cranking the engine for 20 seconds and then see if you have any codes present. Then if you still don't see any codes, unplug the ICP connector and crank it again. If the P1280 code doesn't show up, the reader is not seeing your codes.

Fuel pump comes on with the key? Oil level full? Any blown fuses? Tried swapping the IDM & blower motor relays?

 

I did pull the ICP (thats the one on the drivers side head right?), and cranked for a while, but no codes. How long do I need to crank for? I think I hear the fuel pump (its by the drivers door correct?). Oil level is good, although I did have to refill the HPOP res (I will check that again in the morning). I check all the fuses with a fuse tester, all good. However, the #24 in the engine compartment (PCM) is a solid metal fuse?? I could swap that with another, but I haven't yet (it is very hard to get out). I have not swapped the IDM and blower motor relay - how do I pull the relays? Are they in the engine compartment fuse box? Where is the IDM? I can check the wires in the am.

Thanks!!

 

If you unplugged the ICP (yes, drivers side head) and cranked for 15 - 20 seconds, then it sounds like the hand held code reader you have is not reading the codes. You really need to get it on a scanner that can read the codes. There should at least be a P1280 from unplugging the connector.

I don't have an 01 owners manual in front of me, but it should tell you the location of the relays. They're just big square plastic things that plug in like a fuse does. The solid metal fuse sounds like your PCM diode. There's another one right next to it that runs the AC clutch. Switch those 2 around to be on the safe side.

The IDM is tucked up above the drivers front wheel wel liner. The wires from that go to the PCM connector and to the 42 pin connector (square box with a bolt in the middle of it on the drivers side valve cover)

 

Also, I tried to start after running the block heater for a few hours. Didn't start. I was about 70 deg out.

 

How many miles do you have on the truck? You might have injector problems (poppet problems). Not an expert on this but sure others can help...You can look at swamps diesel they have pretty good technical info.

 

You have got to make sure you have fuel. Pump could be running and no fuel getting to the engine. Drain the filter housing and see if it refills with just the key on. Make sure you have a minimun of 11.0 volts while cranking.

 

It is actually spec'd down around 10vdc. It also depends on temp. It was a lot easier to start my Dad's truck that I took care of for many years here when it was warmer. I sometimes could start that truck when it was barely cranking and if warm for some reason the batteries would wake up?????????? You make a good point on fuel that will not set a code.

 

It takes 10.5 volts to power the PCM. Weak batteries will not set a code either. 10 volts is not enough, period. That is hard on the starter and not enough to to work the IDM.

 

Sorry but I don't agree with you on the 10.5vdc. It also depends on temp and CCA of the battery. If your 10.5 vdc was true I would not of got my Dad's truck started many of times. You also have to look at current.......I agree that it getting toward the low end and needs to be looked at.

 

Could be, just going on what I've read here for the past 5 years and that is that the PCM needs at least 10.5 volts to work.

 

I think the 10.5 volts is just a rule of thumb Barry. You've got to factor in voltage drop and things like that. The manual says a much lower number is acceptable, but the 10.5 is a good reference point based upon the experience of many users here.