noise."MECHANIC: Another Econoline · 1:19am Jan 10th, 2023
This one might or might not be short, just depends on how much I go on and on. So get yourself a drink and kick back
while we learn about a Ford Econoline with an P0720 code.
Y'all may remember a few blogs back, I talked about a Ford Fiasco. I mentioned that we'd worked on two other trucks from that guy, both of which wore worth blog posts on their own. Why do I mention this? Guess who owns this van?
This thing's a 98 Ford E350 Cargo, with a 7.3L diesel. The customer's complaint is that it doesn't shift right (which is true). He had the transmission rebuilt--it's got over 300,000 miles (480,000 km) on the ticker. The rebuild didn't fix the shifting problem; it's the same as it was before.
I don't remember the exact code description, but it was a signal code, not an open/short code. That tells me that the computer is seeing a signal, but it doesn't make sense.
Before I get ahead of myself, certain codes can set based on the value of a sensor being illogical or impossible. Most transmissions have two speed sensors, an input shaft speed sensor (ISS) and an output shaft speed sensor (OSS). Based on those two values, the computer knows which gear ratio the transmission is in, and the OSS might also serve as an input to the speedometer. Since the computer knows what transmission it has in it and what the gear ratios of that transmission are, it'll know if it misses a shift, if there's excessive slippage, etc.
If it's consistently showing a wrong signal, maybe indicating that the transmission has shifted into a gear it doesn't have, the code will set.
Diagnosis is simple. The test for this specific vehicle is drive it and monitor the OSS, if the frequency changes while driving replace the sensor; if it stays zero, fix the wires.
I'd like something more than that, so I do some more digging and find out that the resistance of this sensor is supposed to be 400-750 ohms. That's easy to check--I already know it generates a signal, I already know this Ford doesn't like it (in fact, it doesn't like it before it shifts to second gear), so it's a simple matter to ohm check, and I get a result of about 210 ohms. That's less than 400, so it's bad. It's a Dorman part, and some of their electrical parts are questionable, so we get a new one.
It also tests at 200 ohms.
So we get a Ford one. You'll never guess what that one tested at.
Okay, you probably guessed it tested at 200 ohms.
While it's surely possible to get three bad parts, the odds of getting three bad parts from three different manufacturers—including the OEM—which are all identically bad is basically zero.
Now comes the fun stuff.
Back in the days when repair instructions had to be printed in a paper manual, tech writers were more . . . concise. Two different sources for wiring diagrams are not complete; for example, they show a splice but never say what's spliced into it. One diagram doesn't show the OSS at all, another does but has its signal go to a pin that doesn't exist on the PCM connector. Depending on how this van was sold, it might be running EEC-V (OBD-II) or EEC-IV [for people who don't know, that's like an operating system; it would be like saying this truck might be running Windows XP or it might be running Windows Vista]. If it's equipped like it seems to be, the P0720 is not a code it can set.
Everything says that the resistance of the OSS should be 400-750 ohms, though.
This thing's old-school; instead of a magnetic pickup, there's an actual gear on the output shaft and a gear on the OSS. Could the wrong gear be on one of them?
This is also possibly in the era where the rear axle ratio/tire size could be programmed by the customer. If it was accidentally changed, would that confuse the computer? Would it think that the vehicle speed compared to the input shaft speed didn't make any sense?
At a loss for ideas, we ran new wires without any splices, all the way to the PCM, just to see what would happen. I had no signal on the scan tool, and the speedometer didn't work (on this Ford, the speedometer gets its signal direct from the OSS). Now it set a new code, a P0500, no VSS [vehicle speed sensor]. That might take priority over a P0500; some codes will set before other codes.
When we put the ground wire back on the circuit that was supposed to have one, my signal came back the same as before, and it went back to setting a P0720 and shifting badly.
My manager got the Ford tool; reprogramming the PCM might do the trick, and we've got nothing to lose by trying. The Ford tool communicated with the van just fine, and it started to go through the programming process, then told me 'something went wrong' and asked if I wanted to try again.
Three tries later, it's obvious this thing isn't going to program. Something's wrong in the PCM. Not the answer we want, but at least now we know.
On Fords of this era, I've seen capacitor failures in the PCM. Usually that'll make some signal not quite as good as the PCM wants it to be, and it's often an intermittent problem. Square-wave signals aren't exactly square, for example. I've got no reason to believe this is the case, but I've got no better ideas and the PCM isn't hard to pull on this. It's old enough that the lid can be unscrewed, and blown capacitors on old Fords are easy to spot—there's usually a little puddle of goo around their legs.
This one comes partway out and then it gets stuck and I really had to work it to get it to come out. Eventually it did, and I realized why it was getting stuck: the back of it was duct-taped.
And it had a tail.
The earliest automotive computers were reprogrammed by changing the PROM chip—the brains of the operation. In Fords at least, the second generation had a port in the back where you could plug a programmer in if you needed to reprogram the unit. By EEC-V programming was done via the OBD-II port under the dash . . . but apparently Ford kept some of their legacy ideas, and they also provided a connector on the circuit board at the back of the PCM.
Some companies that made tuners basically built an interface that plugged into this, and could change the computer programming on the fly, or nearly on the fly. This one had a dial which could be turned to one of several different tunes.
I don't know how tuners work, and I hate them. This one might try to reprogram the PCM, or give it a new fuel or shift matrix; it might see the value certain sensors are reporting and change them to make the PCM do something different than it normally would. Maybe it's the best, most effective tuner ever made but something went wrong on it, I don't know. It's easy to unplug, and when I plugged the PCM back in and tried to program it, everything went perfectly.
Here's where sometimes I'd tell you that when I took it for the test drive, it set the P0720 again, but it didn't. It shifted just like it was supposed to, and it didn't set any codes.
Which brings us to lessons learned!
The service information, at least regarding the resistance of the OSS, was wrong.
Tuners are dumb.
Maybe now that it's programmed correctly, it can't set a P0720 anyway.
Diesel powered vehicles, plus individuals convinced their intelligence is greater than what is actually possed, equals incredibly stupid devices with next to no practical purpose.
Tuners aren't stupid, Admiral. The end users? Well... they have a certain lack that they are compensating for... whatever that may be.
I didn't get enough sleep to even pretend to understand most of this, but at least the ponies are cute!
5707906
I feel much the same way.
Can (or should I say, CAN?) versus should. I certainly wish I could go in and modify things in tractors to just make them work... because service calls are *expensive*. On the other hoof, too many times it's the equivalent of 'I have some bolts and bits left over... guess I'm better than the engineers who designed this thing!'
Whatever you do, do not plug the MCP* into the PCM; or else, the vehicle will attack you.
* MasterContronProgram (MCP) from TRON.
5707901
It does.
We see lots of that with lift kits and big wheels and big exhaust pipes . . . I hate dealing with that stuff. Give me straight stock so I don't have to spend days tracking down a problem that was customer-caused.
I will say in this case, the customer isn't the one who installed the tuner; he bought the van recently and probably didn't even know it was there.
A lot of modern cars' tuners go through the OBD-II port; when I worked at a dealer, we'd sometimes cut one of the comm wires under the dash if we suspected the customer had a tuner and then was programming it back to factory to bring it in for warranty work. What would have been smarter--and a lot harder for the customer to figure out--would have been switching the pins for CAN hi and CAN lo.
5707906
Maybe someday I'll write a blog post that explains some of the terminology I use a lot.
Or maybe these are worth reading just for the pony pictures
5707962
Summary: The Admiral eventually fixed a thing, ponies are cute.
5707963
Engineers often give you spare bolts, that's just a fact. I keep them for vehicles where the engineers forgot to put in a bolt, 'cause you never know.
Depending on skill, I don't mind customers fixing their own stuff. However, the skill level of some of our customers . . .
And if, as a customer, you've messed with it, tell the tech what you did. Makes stuff easier.
I will say--'cause I forgot to mention it in the blog post--the guy bought the van with the tuner installed, and he probably didn't know it was there.
5708145
Looking at the collection of cuts on my hands and forearms from just today, I can say that vehicles will maul you even without a MCP installed.
5708153
Oh yes, they absolutely are!
5708152
Ah, nothing like a bone stock automobile. Just as the gods of rust intended.
No compensation needed.
5708218
but if it's stock how will the people with better cars than you know your pee pee is bigger? (or smaller in my opinion)
5708296
And this is why internal plumbing is superior. Also indoor plumbing.
Build it right the first time, you won't have to make it right later. I stand by that.
5708298
It's cheaper and easier to prevent costly reproducible accidents on an external model than an internal one.
5708300
Accidents... yeah, no Tab A for me, thank you. I'll stick to carpet, hold the rug rats.
5708313
You mean you'd rather deal with car gremlins than human ones?
Same.
5708379
Perhaps in the future, as I said the same thing about cats. But, much like my cats, I'll adopt.
No one need call me "mum".
As for automotive gremlins... the closest to a car I get to is my half million mile survivor of an S-10. Everything else has tyres rated higher than my little Chevrolet weighs.
My only experience with tuning was in the ALH platform of Jetta TDIs. They were shockingly tunable to make absurd amounts of torque from a car of that size. The tuners were highly secretive about their programming, but you could double the output torque with the right upgrades. I settled for a lesser one that was still at least a 30% output upgrade.
I upgraded the clutch, and the end failure point became the transmission. 5th died… then 4th. While driving across the country. Driving the last few hundred miles in 3rd gear was “fun”.
5708296
It'd be cheaper to get a decal made of it and stick it on a window, IMHO.
5708423
Mine made over 400k before the rust got it. Original engine and second transmission.
I dunno what you have; mine was a base model standard cab shortbox with a 2.5L and manual everything. Didn't even have a dome light, it was that low-option. It only weighed 2800 pounds.
I've still got it and another truck and a half for spares . . . maybe someday I'll get it running again.
5708596
Besides the big diesel trucks, tuners seem popular with the import crowd. We don't see many of those vehicles in our shop, but I know they're out there. The problem with them is:
Yeah, the automaker usually builds everything to work well together, and when you start trying to get more power out of it, you wind up breaking other things. Find the new weakest component which might never have been stressed in the original design (one of the Ford diesels, I think the 6.0L, can make more power with a tuner . . . but the head bolts can't handle it for too long. The solution is to install head studs, and the good news is that it's only a 20 hour job).
I do know the kind of 'fun' you were having; my old S-10 had a failing 5-speed; synchros were gone from 3 and 5, you couldn't use 4th (it would go in but not come out unless you matched RPMs), and had to hold the shifter to keep it in reverse.
I replaced it with a used transmission that didn't have first gear, and it was a major improvement.
5712059
Mine has the LT trim package, extended cab, 4.3l V-6. Manual everything but the windshield wipers -I remember those things- factory A/C cab, and equipped with a long box.
The only things not factory are the water pump (changed at 310k), clutch (162k and 410k), slave cylinder (410k because clutch), one ball joint (71k), and rear bumpers... lots of them. But, she's solid as a rock... other than the fact her front recently have an argument with a tree.
So... wanna sell a parts truck? I'm looking to buy, as long as the front clip and core support is good.
5712069
Most of the repair work on mine was body-related (Michigan rust). I think it got one water pump around 200k, one clutch and transmission when I had it (about 300k), ball joints, steering linkage, multiple HVAC fan switches. . . .
I got a hood that's pretty decent, and fenders that aren't too rusty on my parts truck. Or at least they weren't too rusty some years ago when I dropped it in the backyard. Dunno about the core support, it's probably crusty but possibly usable . . . it came off 15 years ago.
Legit unless you're nearby enough to drive over and check out what I got, you might do better to get some/all of those parts on LMC truck. Also I should mention I got an 88 and an 89 ( and some of an 84 and some of a 92).
Heh, some years ago when I was trying to get front fenders for another S10, the junkyard wanted to sell me new ones (at the time, about $50 each) 'cause they didn't have any that weren't rusty. I told them they were going on a $200 dollar truck and I was okay with rust; they'd be a better match for that truck if they were rusted instead of new. I just wanted 'not smashed in an argument with a guardrail' fenders for it.
5712077
Well, I could drop by and look, but that's a two-day turnaround. And mine is a '96. So...
LMC truck... time to go looking. Hope the cost isn't more than the truck is worth. It'll still be cheaper than a new truck.
5712060
I am reminded of a car I had in college - a 1.2L (?) Geo Metro - that had no 2nd gear. Every stoplight you had to wind it up to redline and then dump it into 3rd. The alternative was to stall. Often.
5712083
Depending on where you're at, any cost over scrap value (by weight) is worth more than the truck.
Not saying that 'cause I dislike S-trucks, but I NADA bluebooked mine once and it was a negative number. Still ran good and got me where I wanted to go, so it was worth it. It was also the only vehicle I've ever owned that appreciated in value significantly when I filled the tank (if it had been running in 2021, a full tank of gas would have been worth more than the purchase price of the truck).
Quick look at LMC and a guess at what you've got; fenders are $90 each, hood's $140, inner fenders are $40 each. Didn't go hunting for a core support, but if you care about looks you can't see it when all the trim's on; if it's close enough it can work
We should hang out sometime and we can gripe about working on cars and trucks and how much they used to be better and how much better they are now. Show off battle scars and debate how good a hammer the IR231 is. The new composite impact guns are nice on the wrist, but you can't bludgeon things with it like you could with the old ones.
5712098
You make a fair point. But, she's served me well, long and hard. I wanna see her hit 500k, maybe a million if her frame will hold. I think I've spent more than she cost new, and I'm sure that trend will continue.
Thanks for the starting point on cost. Definitely cheaper than the scrappers.
Sounds like a good time. I'll bring the rum, once I learn how to take a day off. And I'm not on the "on call" list for work... whenever that happens.
As for air wrenches, I only have two; a IR one inch drive (purched used), and a Sears Roebuck half inch drive (purchased new from the catalog). Those are my survivors. My most recent air wrench (read victim) was a central pneumatic... a surprising service life of four years.
I've had my fair share of IR tools. They all made good improvised bludgeoning devices, with the exception of the air compressor.
5712109
Obviously there's more to the value of the vehicle than its actual book value, so there's nothing wrong with fixing it as long as you can. We had a guy who was up here working on a pipeline; he had a 90s Chevy 1500 with 1.3 million miles on it. He hit a deer, the truck was obviously totalled, and he paid the body shop to replace everything on the front end it needed.
Heck, if you're feeling frisky, you can re-frame it if you need to. Or reinforce it. In theory you can keep rebuilding it indefinitely.
Heh, I know that feel. Last year I took the most days off I ever have in one year, 'cause they can't fire me and we were already a week or more behind on orders, so a couple more days wouldn't hurt.
I've got three daily drivers (in the 1/2 inch size), two of the composite IR guns, and a Snap-On I bought used. One of the IRs is badly in need of repair; it doesn't always go in reverse. I've heard that the CP are decent quality for the price, but honestly the IR composites are a good value for the money, too. Mine are abused and I almost never lube 'em.
My favorite improvised bludgeoning device is a 2 quart stainless steel thermos from the seventies or eighties (I'm guessing). I've fixed two cars in the field by hitting things with it.
And it keeps my coffee warm
cdn.discordapp.com/attachments/879533986303606834/1071632654354628628/FRVhpRWHdldX1va2FLVbhOytJM7txVRmwJT1dXEqPwE.jpg
5712219
Book value means very little to me at this point in life. And she wouldn't be the first truck I've re-framed. I had a '74 Custom Deluxe 10 that I replaced every part of the cab but the VIN plate. I replace, built, or otherwise fabricated more beds than I cared to count. I think the only part I never replaced at least twice was the engine.
It's not a matter of can I anymore, it's a matter of do I really want to.
Oh, I can still be fired, and im sure I eventually will be fired. But that's going to just be "slightly early retirement" at this rate.
Well, mine aren't daily drivers these days. But, they still get used. I just found an old Craftsman in one of my old boxes. It works, so I'm gonna work it.
Automatic oiler for the win... because I don't have enough brains left to remember to do it.
I'm fond of my grabbit hammer... if I can grabbit, it's a hammer.
Nice sticker on your thermos though. Mine has... dents. Lots and lots of dents. And a couple of weld burns. I never actually thought to put stickers on it.
... I like it.