I have an '02 GMC 2500, 4x4 Duramax diesel. The check engine light comes on when in towing up-hill. Anyways, after un-hooking trailer and starting truck up later, the light goes off. Doesn't come back on again until towing up the hill. Called dealership and they want $300- just to hook it up to the diagnostic machine! Is this crazy or is that what people are paying for this!??  I am the second owner of this truck and had the Glow plugs all replaced and all the fluids changed. Fuel injectors are original as far as I know. There is no white smoke coming out of tail pipe when I start it and no "pinging" sounds coming from the engine. (Which is what I was told  would happen if it was an injector) It does however shoot out black smoke when I "get on it" (passing gear or up-hill) I just had the fuel filter changed and the black smoke is nowhere near as bad as it was before.(again..black smoke only in passing gear)A friend hooked it up to their "diagnosis machine" and it read a 1093 code which is "fuel rail system". Any ideas what it could be? Could it possibly be just 1 injector or what? A friend of mine has an '05 that she had to have just 1 injector replaced. But..she said she could hear "pinging". And told me, " you will know when an injector goes".

Also, while in tow haul mode, tranny is not shifting until it gets to the 2.5 RPM. Is this normal? It sounds like it is not shifting when supposed to. This is between the speeds of 30-50 MPH that it does this. Only the up-shift though. The down-shift is fine. And this is ONLY in tow haul mode that this is happening.

Black smoke on a diesel is just unburnt fuel being exhausted. That is why it is so common to see on Tuned engines where the injectors are turned up to higher levels.  The newer the engine the better the computer and injectors are at giving the exact amount of required fuel and not injected excess that turns up as black smoke.  Couple that with the Diesel Particulate Filters that were installed on all diesels after 2008 and you see very little black smoke on modern diesel engines. A bad inector can cause black smoke, because it is feeding too much fuel, but it is not the only cause of black smoke.

Tow/Haul, will cause the transmission to hold gear longer,. Keeping your engine in higher RPM for the extra power needed while towing.  So yes it is expected to see your tranny not shift at lower rpms like you would when your truck is empty.

If you know the DTC Code, Just call your service advisor and ask what causes it and what the estimated repair is. I have not had any check engine lights in two years since I bought my 2011 F350, But I had called several times on previous trucks and found the service advisor very helpful in telling me what the code ment and what the probable repair would be. It's part of developing a relationship with your service advisor. On several cases, I just came in and bought the parts and did the repair myself. No hard feelings with the advisor for telling me what the code was and how to fix it.

As far as paying $300 to hook up and read the code. You can buy several products that will read the code for you for that price. I use the Edge Insight on my truck (they sell for about $300). Acts as an extra guage most of the time, displaying oil and transmission temps.  But if I ever see the check engine light it will display the codes and even clear a code if I need it cleared. When I had a HPOP failure on my 2006 6.0L engine, Truck was dead, Would not start. Called my service advisor and gave him the code that the Edge Insight had retrieved. He told me what the problem was and suggested I clear the code and start the truck and drive it in for repairs.  I cleared the code, Truck then started, I was able to take my trailer home and then drop the truck off at the dealership for repairs, A whole lot better ending that having a tow truck come get me and worrying about how to get my trailer home.

AZgrulla,

 Thanks, I will try the dieselplace forums.

 Did your truck make any sounds that you could identify with the turbo solenoid? I do hear every once in a while...usually when the truck is cold, a whining sound? Like the radiator fan or a blower of some kind is coming on and then goes off. And I don't think it is the radiator fan either...it's just what it sounds like though. It doesn't do this all the time though but it is usually when I first start the truck up and then drive off.

call a different dealer.

I used to live less than a mile from a chevy dealer but their service is about what you are describing.  I called the GM dealer 30miles away and they are always better

Code 1093 from what I can see is: P1093: Fuel pressure low during power enhancement

I got that from here: http://www.duramaxforum.com/forum/911-problems-forum/1164-check-engine-light-dtc-1093-a.html 

Hope it helps.

Thanks Jeeppir. That is what I was afraid of, and of course it is no longer under warranty too right? It has only 84k on it. Ughhh. Well, it just sits now cause I don't have the money to get it fixed.

I don't have any smoke or smell of oil in the diesel though. At least not yet? Or is it diesel in the oil? Just had a friend change out the fuel filter and there is black something on the old filter. He tore into the old one to see if he could find pieces of metal or what not. He doesn't think it is oil though(on the filter)What else might it be?

The engine will actually warm up faster if you just drive.  No hard acceleration, no racing, just drive.

On mine, I can have the engine coolant warmer with 1 minutes of driving than I can with 10 minutes of idling. So start the engine, let it idle long enough to get the oil pumping and circulating and then drive. By getting a little turbo boost going, Your combustion temps will climb dramatically which will heat the engine block much faster, The coolant is working at cooling the block and you will see your coolant temps climb much faster.

Diesel engines produce soot.  The oil that you use in a diesel engine is designed to carry a high load of soot in suspension and still provide lubrication.  That is why you don't use the same kind of oil that you would use in a gas engine. Make sure the oil you use is designated for a diesel engine. New oil goes into the engine with a golden color and will turn BLACK very quickly.  After 5000 miles everything in the oil filter will be black from the soot carried in the oil.

Equinetransport,

I have an '06 2-horse all aluminum Classic trailer ( gooseneck)It weighs with nothing in it 4400. So, nothing for my truck to pull with 1 horse and my camping gear. I'm not losing power up-hills yet..well it is slowing down a little but if I press the pedal it goes. Anyways, No bad sounds...just that annoying "service engine soon" light comes on, on the hills. These are slight hills, nothing major. No ruff engine ride yet anyways.