DTC 35 - Help! (oldie but goodie?)

[moondoggie]

[font=times][size=+]Good Day!

I was inspired by the thread

[moondoggie]

Posted by BUZZ (Member # 863) on 08 September, 2003 11:17 AM:

I wonder if a worn timing chain will set these 35 and 36 codes. Erroneous type codes, I sometimes get as well. I am running a FSD cooler with a 2 year old 20,000 mile IP. All grounds and related items function correctly. Engine does not start well since pump replacement. I wonder if slack timing chain is responsible for poor cold starts.
Buzz

[moondoggie]

Posted by moondoggie (Member # 5044) on 08 September, 2003 01:50 PM:

Good Day!

Timing chain causing DTC 35 and/or 36, or poor cold starts? I sure couldn't say, but it doesn't sound impossible. I can tell you that the ONLY symptoms I have are the SES light coming on, & loss of cruise control (which happens whenever SES is on, apparently). This truck starts & drives perfectly. In fact, it's quite noticeable how much better it cold starts than the 95 Sub.

Last weekend I cleaned up all the grounds I could find, so I'm in data-collecting mode now. The real fun (sick humor) of this kind of problem is you never know where it's going to lead you. I thought I had a definite IP problem; now I'm not so sure. I will not report any data until I'm pretty sure the data is solid; I will report any data as soon as it is solid.

Blessings!

[moondoggie]

Posted by BUZZ (Member # 863) on 08 September, 2003 06:27 PM:

The only symptom I have is SES and associated loss of cc. The cold start seems retarded. I only get a 35 or 36 on occasion, more so when the outside temp is in the 50's or lower. During the summer months no codes on cold start. After the truck is at full op temp in any weather condition, I get no SES. I am with you, I don't think the IP is the culprit.

[moondoggie]

Posted by ucdavis (Member # 9352) on 08 September, 2003 10:27 PM:

re: cleaning behind fuel solenoid cap- this is not for the faint of heart. You are opening up the IP & must be clean-room picky about how you act with it open. I disassembled a dead IP & found piled up junk at the solenoid plunger that had to affect pulse timing; it looked like nylon plastic that had been ground up, along w/some fuel debris. I believe you can do this w/out affecting timing, but can't go any further cuz the fuel solenoid itself must be set for a tolerance-driven headspace to generate correct injection pressure.
re: dirty fuel, it was my speculation that junk could interfere w/the plunger to cause too long a pulse; perhaps too short is also possible from filth in IP.
Note about fixed pulse width: this is "back-up fuel mode" or limp mode. W/this you have lousy power on acceleration. If you have no power loss (you might not notice w/out a load) you don't have fixed pulse width.
Good luck, anxious to hear more.

[moondoggie]

Posted by Uncle Wally (Member # 8821) on 10 September, 2003 01:36 AM:

On my 94 the ground strap from the body to engine and then the frame is on the passenger side head by the downpipe. The straps are no very long and seem to get dirty easily, so they are hard to recognize in low light conditions.

Waldo

[moondoggie]

Posted by tom mac 95 (Member # 8962) on 10 September, 2003 08:18 AM:

I recently checked all engine grounds on my '95. The one Wally mentioned--passenger head/frame/chassis(firewall) was the only one that was clearly "bad". The screw into the frame rail(near downpipe) was loose. This more likely to affect tail lights than engine....

[moondoggie]

Posted by moondoggie (Member # 5044) on 10 September, 2003 12:40 PM:

Good Day!

Last weekend I did some of the list, so now I'm in data-collecting mode. I'll have something more here within 3 weeks or so. Thanks for all your input.

Blessings!

[moondoggie]

Posted by moondoggie on 06 October, 2003 07:11 AM:

Good Day!

****************************** THANKS! ******************************

It's really not a big enough word. On 4 October, I did steps 1-3, 5, & 6. Basically, I cleaned all the connectors listed that I could find, & the grounds listed. The SES hasn't lit once since.

With the exception of one two-wire connector in that mass of connectors at the back of the engine, all were the kind with the weather seal, & all of these looked like the day they were made. I squirted some Cramolin DeoxIT D5 in each connector & reconnected them.

When cleaning the ground connections, I had a few variances to the list. 1) Under dash - I'm not sure I found this one or not. I had the dash out of the truck some time ago, & not everything is where it should be. I found a black wire connected to the steel dash framework under one of the diagnostic connector screws, but am not sure this is the one on the list of to-do's. 2) I never found a ground from the engine to the chassis. I found one from the rear of the intake manifold to the firewall, & it was a little loose. I found the one Uncle Wally & tom mac 95 mention, by the turbo downpipe, from frame to firewall. This was not loose, but when I went to put it back together, the threads in the frame were stripped. I drilled & tapped a new hole & used a new bolt.

I put external tooth lockwashers under all ground connections (most didn't have these), & squirted dielectric grease everywhere.

This was an interesting hunt. I was absolutely convinced that doing these things (cleaning grounds & connectors) was going to have no effect on my problem - I did them because the combined wisdom of the Page (& Jim's article) said I should. I was recording data on a clipboard in my truck, & what I was seeing was SES on at start, fading to SES out after 5 - 15 miles of driving. This looked to me like impending IP failure. In support of this, twice my wife took the truck to visit her sister about 2 1/2 hours north of here, & when I got the truck back, the SES would be on all the way to work & back for 2 - 5 days. It would then gradually go back to the previous symptoms. She doesn't use the Gear Vendors Aux. OD, so revs are higher when she drives on the highway, plus she drives faster than me. (Yeah, I know, so does everyone drawing breath.:) ) Based on the connectors looking so good, I'd bet cleaning the grounds fixed the problem, but I was really wrong before...

If anything weird happens that seems like it might be related to this, I will be sure to update this topic. It seems like it might be helpful to DP members to keep related info in one location.

ucdavis: I can't tell you how bad I feel that I didn't have to open up the back of my IP. - Actually, it sounds kind of interesting, but would put my daily driver at significant risk, so I guess I'll have to live without this level of fun. I sure wish I'd been in on this 6.5L TD stuff in the early days, I think there are products that would have had a market & helped folks a lot, but now everyone's buying a DMax. I'll be driving this one until I can't anymore.

As I said, thanks isn't a big enough word. Jim, ucdavis, brittanic, Uncle Wally, & all those whose posts were lost, plus all the other willing members: Imagine what this kind of problem costs an uninformed owner. They'd probably start by replacing the IP (probably $1800.00 at a dealer) & not solve the problem. I spend NOTHING but time & fixed my truck.

Blessings!

[moondoggie]

Posted by JDave (Member # 10481) on 06 October, 2003 09:35 AM:

Brian,
I would like to add my .02 as well after have DTC 36 get progressively worse over the last year and looking at a new IP. I replaced my intake manifold with a non EGR manifold and pulled and cleaned the bolts that handle the battery grounds as well as the ground in the back corner. This ground was tight on the bolt but not tight in the head and very oily. After clean up and installation my code disappeared while driving. I have seen two lights which -I haven't checked, after the truck sits for 2 days apon startup for about 10 seconds and then disappears. So I think it is the ground at the intake in the back that had some kind of faulty connection as the others didn't seem that bad. I am very relieved as I did this work back at Labor Day and it still is working good. I wonder how many IPs get changed for bad grounds that are taken care of when the intake gets removed and cleaned and installed. Any how, I think you've got it this time.

[moondoggie]

Posted by curmudge1 (Member # 5699) on 06 October, 2003 03:30 PM:

FYI, FWIW, my story didn't work out quite so well: I had the DS4 injection pump fail in my 94 6.5TD Blazer about a year and 1/2 ago. I don't do major mechanical work, so I had a Chevy dealer, recommended by local Stanadyne distributor & who diagnosed the failed pump (after about 130-150K miles of life, iirc), install a refurb pump from Diesel Injection in TX (DP advertisers) -- after a couple months, it showed DTC 35s & set the SES (after running a bit at first, later almost right away after starting). Diesel Inj sent an advance replacement & I had it installed (different mech) & it started doing the SES & DTCs again after a month or so... I AGAIN checked the connections, but not the grounds. So, tried another dealer, busy GMC dealership... they installed a NEW pump & an updated chip for about $2200 (big OUCH), and Diesel Inj. took the pump back for a refund (GREAT SERVICE, I buy my SPF there, I recommend them). 'course I was out the labor $$ from the two prior installs, plus all the aggravation.

Both the Chevy & GMC Dealers said that they only install NEW pumps, no more rebuilds, because of problems. And, the Stanadyne dealers don't seem to be too savvy about the 6.5, they just know the pumps; Diesel Inj. rep said they just checked my returned pumps & sold to someone else & they report no problems (arggh).

I do recall one tidbit from somewhere that said that the 94s were more picky about the injection pulse width -- maybe that was why the GMC dealer replaced the chip? Anyway, it's been fine, no problems since (knock on wood). And I'm glad someone else got their problem fixed with just cleaning up electrical connections. Maybe my problem was the ground connections? And/or the chip? Are there any posted pictures of these ground connections, to help me find them?

[moondoggie]

Posted by ucdavis (Member # 9352) on 06 October, 2003 04:21 PM:

NP Moon, That's why we're here.
So here's a thought for the checklist:
Lotta folks say OK, I'll clean the grounds; where are the grounds?
Why not obviate the search & start the ground quality process w/new grounds to dash, head2frame, etc for any that you can't find? All the checklist would need is a list of the ground strap locations & if you don't find one conveniently, cut a piece of #8 wire, put some suitable ends on it, choose a bolt (maybe choose the end locations B4 cutting wire), clean up & tighten the connections. No more fumbling to find stuff that might have been removed by some previous owner or tech.

[moondoggie]

Posted by Uncle Wally (Member # 8821) on 06 October, 2003 08:27 PM:

Moon,

My 94 manuals say:
1 ground - pass side head to frame and body (this is a braided non insulated wire right by the downpipe.
1 ground - passenger side battery to body
1 ground - wireing harness to dash right above ALDL
1 ground - under bed drivers side rear near bumper

Since the manual is somewhat difficult to decipher, I'm sure I have missed some. But these are all on my 94. The one by the turbo downpipe is what I suspect are most peoples problems as the A/C canister has ice on it when used, it drips down on the frame connection when it melts. When exposed to the heat of the exhaust, corrosion rates increase. Mine were/are bad. I installed one from the front of the drivers side head to the frame and from the rear of the head to the cab.

Waldo

[moondoggie]

Posted by moondoggie (Member # 5044) on 07 October, 2003 09:23 AM:

Good Day!

JDave: Great tip. Makes you wonder if curmudge1's problem might have gotten fixed when they R/R the intake manifold? Stranger things have happened...

curmudge1: I caught one comment here once about newer trucks having a wider window for 35 & 36 codes. Maybe you got the PROM that takes care of this. Do you have a part number? Does anyone know more about this? I guess 130-150K on an IP isn't too bad, but it's frustrating to never know if the original pump even needed to be replaced or not. You must be a pretty patient person. I might have put a torch to mine somewhere during your story.

I'd be glad to post pictures, but I don't have a digital camera - in fact, getting email is about the limit of my technology.

ucdavis: One does have to be aware of ground currents. By adding grounds at different locations than factory, & the factory ones still being there doing some of the job, there is a small chance (I'd say 1 in a million) of ground currents adding problems instead of eliminating problems. (Remember, you're not paranoid if they really are out to get you.)

Uncle Wally: I moved the one by the downpipe to the side of the frame rail - that's where I could get access to drill & tap the new hole. Hope this works for awhile.

Blessings!

[moondoggie]

Posted by moondoggie (Member # 5044) on 09 December, 2003 11:10 AM:

Good Day!

Update: It's been about two months, & not one SES light or problem with my truck! As before, during, & after this event, my truck runs perfectly.

ucdavis: Sorry I didn't try cleaning behind fuel solenoid cap. It turned out to be unnecessary which is good, but it might have been fun to try. :eek:

I'd sure like someone to explain the symptoms I listed in my 6 October here (where it looked like a thermal intermittent). Pretty weird.

Again, thanks to all. I hope this topic's being in the forum will make life easier for someone with similar symptoms who finds in by using "search."

Blessings!

[Bnave95]

Happen to catch up on this,good job moondoggie:)
I myself had been running this 35 for close to a year and gave up trying to solve it. I remember your posts and the check list and had done all that could be done. So I talked to JK and he said others had the same issues and they just ran it till the pump went dead.
Not to long ago I posted that I did a spring cooling cleaning on the system and went for 180* to 195* stats. Code 35 use to be a on and off and got to the point of just staying on. Got use to it. City driving would not light the ses 35, only highway driving above 45-50mph.
Don't ask me why,but after changing to the 195* the code has gone away.
I have upped the Power Service running the gray bottle now from 4oz to 6oz every 20gal.
Now and than I check for codes but they are all clear. So after running a year + and thinking I'm not going to put a new one on cause the truck ran just fine the code it gone:confused:

[moondoggie]

Good Day!

Your post is why I went to all the work to get this search-able on our forums.

At the price of replacing the IP, I was going to run it 'til it died anyway, but I sure did miss my cruise control while I had the code.

Blessings!

(signature in previous post)

[Bnave95]

Good Day!

Your post is why I went to all the work to get this search-able on our forums.

At the price of replacing the IP, I was going to run it 'til it died anyway, but I sure did miss my cruise control while I had the code.

Blessings!

(signature in previous post)
Yes, my cruise would kick out though was able to reset with out cycling the key.To date the pump has 110,500.