ever had an IWE solenoid short and kill the PCM?

Joey Kaylor · March 19, 2008

i had this 04 F150 in today that was kicking my balls. pulled it in, had the 4wd inop complaint. verified hubs not engaging, saw the old style solenoid, and ordered a replacement unit from Motorcraft.

checked, and i pulled a C1980 out of it. ran a quick test to verify that i had 12v on one terminal, and popped a new solenoid on. when i tried to clear the code, it was still in the PCM.

i didnt think much about it, but when i was testing it out, the damn thing still didnt work. pulled it back in, did a loaded test on the control circuit, and found it to be flowing current well. this appears to be a rather simple circuit according to the WSM, and the only thing else i can see is a burned out driver in the PCM.

or am i missing something?

our local dealer refuses to acknowledge any of my diagnostics, and will usually throw several parts at a problem if i send it up for warr. repair before fixing it correctly. this truck has 34k on the clock, but is out of warr. by time (a year i think). but, if its a burned out driver in the PCM, its technically covered by the 8/80k warr on emissions devices, if i am seeing it correctly.

Mekanik · March 21, 2008

I have fixed a few of these IWE problems. Does the solinoid energize when commanded by the PCM? Does the solinoid work? Does it apply vaccum to the IWE wheel ends? If it does, will the system hold vaccum? I have seen a few vaccum leaks right by the solinoid. A smoke machine can be very helpfull in finding the cracked vaccum line.

Joey Kaylor · March 21, 2008

the solenoid will not energize by the PCM when commanded by IDS. i can apply a ground, and the solenoid will energize and actuate the hubs.

the circuit is solid from the solenoid to the PCM, but unless there is some protection strategy that i am not aware of, it looks like its got a fried PCM.

Mekanik · March 22, 2008

Is there a pid that shows when the PCM is commanding the IWE solinoid?

Can you see the 4X4 switch working properly?

Thw wire from the PCM to the IWE solinoid isn't grounded is it?

It does kind of sound like it could be a PCM. I'm always very hesitant to replace a PCM.

Joey Kaylor · March 22, 2008

yes, the PID changes when commanded. the weird thing is, most of the time when there is a water contaminated solenoid, the 4hi light will not come on. this one does. it will go to all positions, and everything is changing state like it should, aside from there not being any command on the IWE solenoid.

i can manually command it with a power probe, and it works fine. its like there is a dead driver in the PCM from what i can see.

when it was in the other day, i spent about an hour doing diag to confirm my diagnosis, and it will be back in later next week for a service, so i will double check it again before sending it to the dealer for a PCM.

of course, they will likely throw a couple of other parts at it first before confirming my diagnosis, as i have had experience with in the past. hopefully, they will agree and fix it.

Jim Warman · March 22, 2008

Here's about the easiest thing you can try... and all you need is a voltmeter and a couple of suitable probes (Mac Tools has a couple or three really marvelous probe kits for DMMs.. I bought two of their kits and rarely reach for the Ford probes any more.... Each one of these kits cost more than my DMM but well worth the expense).

Then, let's get some basics out of the way... Learning to read the wiring diagrams will help, though the new ones don't show enough of what is "roughly" happening inside the module. For this case, we can see that this very likely isn't going to be a voltage divider circuit - looks like a simple NPN transistor turning the ground on or off.

If I say measure something to ground... I mean to the battery negative terminal and NOT to something that looks convenient. Same thing goes for a source of B+.... Straight to the positive terminal. Under 10 bucks and you can have a 50 foot fused pair of jumpers.

Before you begin volt drop testing, ALWAYS measure battery voltage first- ALWAYS. If your testing is starting to take a little longer than you thought, recheck battery voltage occasionally. If the voltage drops off to the 12.2 ~ 12.4 range, start thinking real hard about putting it on a charger. You are getting outside of the designed operating range and odd things start to happen.

ALL measurements are taken with the system fully connected and turned on. You have to do this right, or your measurements aren't going to mean a damned thing.

Three measurements is all it will take to decide where to look for the problem.... Backprobe both sides of the IWE connector with the key on and the selector in 2WD (this should ground the control side of the circuit). If everything is working properly... you'll see close to B+. If the solenoid is open but the circuit is OK... you'll see close to B+ (and no... that isn't confusing if you only think about it).

So... we got 0 VDC... No problem... Take the probe from the ground side of the solenoid and touch it to battery ground. If we get B+ we move on... Anything else and we investigate the power side of the circuit.

Moving on, we re-insert the ground side probe... and take the power side probe and touch it to the battery positive cable. We should see B+ (remembering that we are STILL KOEO and switch in 2WD). In this case... I believe that we wont...

There's our three measurements to detemine if the problem is the "load" (in the case, the IWE solenoid), the power supply or the control circuit...

Our last test showed that the control side of the solenoid isn't grounding.... so we can gain access to the back side of the plug on the PCM and backprobe that connector. One lead of the DMM to that pin and one lead to battery ground. If we still see B+, that driver isn't switching... Four volt drop tests... elapsed time about .3ish???

Some words of caution.... The IDS sometimes "remembers" things we don't want it to. After repairing a hard fault, I like to close the session entirely and start from scratch. When doing the KOEO self test, the 4WD selector switch MUST be in the 2WD position.

The 4WD indicator lamp on the cluster is an important clue. If this lamp does NOT illuminate, there is every chance that the PCM will assume that the front driveline is not up to speed and will not command IWE operation.

I'm not sure of what PID is being monitored... If we are looking at the MSS PID, all we get to see is if the PCM is processing THAT info... We still need to look at either the contact plate PIDs or at the computed transfer case position PID (if available) to see if the transfer case is actually entering 4WD.

I apologize if this is insultingly basic to anyone... I am doing laminate flooring this weekend and I'm looking for any reason I can find to avoid kneeling down for a while....

Bruce.... this would be a great use for some of that classroom software....

Jim Warman · March 24, 2008

Well, now.... I managed to screw that one up - and nobody noticed?

Of course the preconditions must be met for the PCM to DE-energize the solenoid... Sorry for any confusion.

LARRY BRUDZYNSKI · March 25, 2008

Confusion??? What the F..., I'm just a parts guy, how about talking in english??? I would really like to know what you are talking about in laymens terms.

Jim Warman · March 25, 2008

Confusion??? What the F..., I'm just a parts guy, how about talking in english??? I would really like to know what you are talking about in laymens terms.

If I did that, you'd expect us to teach you the "secret handshake".... /forums/images/%%GRAEMLIN_URL%%/grin.gif

There are several different ways to use a voltmeter... one way will find the probelm... the other ones generally lead us astray.

Three properly performed volt drops will identify whether the concern is power, ground or load. Two or three more will nearly have the concern fall into your lap.

FWIW, (not sure how others feel on the subject) I don't like to overlay circuits. If one wire in a harness is hurtin' chances are that others are close behind..

Tony302600 · March 26, 2008

There is no such thing as ohming out a wire in my eyes. It get's a voltage drop test. (ford is following that soon, you watch). On an engine harness.....if there is more then .2v drop then u have an issue.

Side note: The new SJB in the 08 SD's is EXTREMELY sensitive to current draw. If there is too much current draw (hotline wouldn't tell me the exact spec) in that CKT, it will shut that CKT down. I had a headlamp problem on a 08 with a aftermarket plow package installed. They used one headlamp connector to supply voltage to the aftermarket ones and to the other headlamp. The concern "Headlamps take 5seconds to come on" Resolution: They burnt out the SJB by overloading the CKT. When turning the headlamps on and there is a 5second delay...the SJB box senses a failure, does a self-test on the headlamp ckt, throw's a code, then put's the headlamps on for safety. All in that 5second span. So if anyone of you guys have that problem, there's why.

LARRY BRUDZYNSKI · March 27, 2008

So in other words the Voltmeter still... Is the most valuable tool that I bought 20+ years ago, in my tool box, even working on the newer vehicles???

Jim Warman · March 27, 2008

Tony... you ain't kidding.... In spite of the TSB that says you can't put illuminated running boards on a Job 1 08.... they had me do one anyway...

Hook up the lights so that they do what you want and they will work perfectly.... once. The SJB makes note of the over-amp condition and will refuse to turn that circuit on a second time. Clear the code and the lamps will work perfectly...... once.

Larry, used PROPERLY, the voltmeter is going to be one of the most important tools in the box for a long, long time.

LARRY BRUDZYNSKI · March 27, 2008

Thanks Jim(GRAMPY)

Keith Browning · March 27, 2008

There is no such thing as ohming out a wire in my eyes. It get's a voltage drop test. (ford is following that soon, you watch). On an engine harness.....if there is more then .2v drop then u have an issue.

Side note: The new SJB in the 08 SD's is EXTREMELY sensitive to current draw. If there is too much current draw (hotline wouldn't tell me the exact spec) in that CKT, it will shut that CKT down. I had a headlamp problem on a 08 with a aftermarket plow package installed. They used one headlamp connector to supply voltage to the aftermarket ones and to the other headlamp. The concern "Headlamps take 5seconds to come on" Resolution: They burnt out the SJB by overloading the CKT. When turning the headlamps on and there is a 5second delay...the SJB box senses a failure, does a self-test on the headlamp ckt, throw's a code, then put's the headlamps on for safety. All in that 5second span. So if anyone of you guys have that problem, there's why.

0838 - 2007-2008 MULITPLE VEHICLES - SMART POWER DISTRIBUTION JUNCTION BOX (SPDJB) CIRCUIT FAULT DISABLE FEATURE

THE SMART POWER DISTRIBUTION JUNCTION BOX (SPDJB) IN CERTAIN 2007-2008 VEHICLES HAVE BUILT-IN FUNCTIONALITY TO DISABLE CIRCUITS. IF A CIRCUIT FAULT IS DETECTED, A DTC FOR THE AFFECTED CIRCUIT WILL BE SET IN THE SPDJB AND THE CIRCUIT OUTPUT IS DISABLED UNTIL THE DTC(S) ARE CLEARED AND THE SPDJB PASSES A SELF TEST. IF ELECTRICAL SYMPTOMS ARE PRESENT, PERFORM A SELF-TEST ON THE SPDJB AND CHECK FOR DTC'S. FOLLOW NORMAL SHOP MANUAL DIAGNOSTICS TO ISOLATE AND REPAIR THE AFFECTED CIRCUIT(S). ONCE THE FAULT HAS BEEN REPAIRED, CLEARING THE DTC(S) AND PASSING A SELF-TEST OF THE SPDJB WILL RESTORE OUTPUT ON THE AFFECTED CIRCUIT. NOTE: REPLACEMENT OF THE SPDJB SHOULD NOT BE NECESSARY TO RESTORE FUNCTIONALITY AND SHOULD ONLY BE DONE IF DIRECTED TO DO SO BY SHOP MANUAL DIAGNOSTICS.

Tony302600 · March 27, 2008

Originally Posted By: Tony302600

There is no such thing as ohming out a wire in my eyes. It get's a voltage drop test. (ford is following that soon, you watch). On an engine harness.....if there is more then .2v drop then u have an issue.

Side note: The new SJB in the 08 SD's is EXTREMELY sensitive to current draw. If there is too much current draw (hotline wouldn't tell me the exact spec) in that CKT, it will shut that CKT down. I had a headlamp problem on a 08 with a aftermarket plow package installed. They used one headlamp connector to supply voltage to the aftermarket ones and to the other headlamp. The concern "Headlamps take 5seconds to come on" Resolution: They burnt out the SJB by overloading the CKT. When turning the headlamps on and there is a 5second delay...the SJB box senses a failure, does a self-test on the headlamp ckt, throw's a code, then put's the headlamps on for safety. All in that 5second span. So if anyone of you guys have that problem, there's why.

0838 - 2007-2008 MULITPLE VEHICLES - SMART POWER DISTRIBUTION JUNCTION BOX (SPDJB) CIRCUIT FAULT DISABLE FEATURE

THE SMART POWER DISTRIBUTION JUNCTION BOX (SPDJB) IN CERTAIN 2007-2008 VEHICLES HAVE BUILT-IN FUNCTIONALITY TO DISABLE CIRCUITS. IF A CIRCUIT FAULT IS DETECTED, A DTC FOR THE AFFECTED CIRCUIT WILL BE SET IN THE SPDJB AND THE CIRCUIT OUTPUT IS DISABLED UNTIL THE DTC(S) ARE CLEARED AND THE SPDJB PASSES A SELF TEST. IF ELECTRICAL SYMPTOMS ARE PRESENT, PERFORM A SELF-TEST ON THE SPDJB AND CHECK FOR DTC'S. FOLLOW NORMAL SHOP MANUAL DIAGNOSTICS TO ISOLATE AND REPAIR THE AFFECTED CIRCUIT(S). ONCE THE FAULT HAS BEEN REPAIRED, CLEARING THE DTC(S) AND PASSING A SELF-TEST OF THE SPDJB WILL RESTORE OUTPUT ON THE AFFECTED CIRCUIT. NOTE: REPLACEMENT OF THE SPDJB SHOULD NOT BE NECESSARY TO RESTORE FUNCTIONALITY AND SHOULD ONLY BE DONE IF DIRECTED TO DO SO BY SHOP MANUAL DIAGNOSTICS.

That's a SSM i went off Keith, but Hotline actually built the Headlamp CKT (he said they can do that in their office), and put a faulty SJB they had in the CKT. That's how he (the engineer) and I found out that with no DTC's and the concern still there, the SJB has to put the light's on for safety, even if a fault is indicated.

Keith Browning · March 27, 2008

And I was hesitant to create an SSM archive. Between that and your post I just learned a lot about the SJB I was not aware of.

Joey Kaylor · April 20, 2008

i figured i would put up an update to this truck.

i advised the customer that since it was over on time for the 3/36k warr, they would likely give him a hard time on replacing the PCM for a 4wd inop issue. even though the PCM is considered an emissions component and covered under the federal 8yr/80k warranty, i had a feeling that they would say it was something i did when changing the solenoid.

of course, i was right. cust. brought vehicle to dealer, they had for two days. said incorrect IWE solenoid was installed, and a new solenoid fixed it. the funny thing is i had their parts dept get me the solenoid, and it was the same PN that they installed and charged the customer for.

two days later, i get called from a PISSED customer telling me his truck is stuck, and to get it out.

bring it to the shop, the hubs aint engaging. verified power to the solenoid again, verified no switching ground.

i said to hell with it and ordered a PCM. after the normal clusterfuck of trying to find a second key from them to program the PATS system, i made another one.

truck works perfectly now. driver was blown in the PCM.

now, i get to try to get paid for this 500 dollar PCM that i installed. i dont even care about the labor, just want to be reimbursed for the part.

i do not understand why they feel the need to do anything in their power to say that the independent didnt fix it right.

Jim Warman · April 20, 2008

Joey... I went back over this thread... something that's been chewing at my mind...

The defualt position for this solenoid is <OFF> (i.e., no vacuum sent to the hubs). With no vacuum commanded to the hubs, the IWEs should be locked. It is when the PCM commands the solenoid <ON> that the hubs unlock for 2WD operation.... And this, I think, may be the reason for some of the pain you are enduring.

We are used to having a circuit turn <ON> for us to get a desired action... In the case of the IWEs, it can become easy to forget that we need the circuit to turn <OFF> in order to get our desired action.... Your stuck customer only ever needed to unplug the electrical connector from the solenoid to get unstuck.

You diagnosed a PCM... quite correctly from the sound of it since the IWE solenoid driver appears to have shorted to ground.

But it becomes painfully obvious that the dealer tech didn't road test the truck to verify the repair (for this concern, this would be to drive in a tight circle in two wheel drive and then try to drive in a tight circle in 4WD) nor did he follow the PPT for the code retrieved.

In any industry, we will find those that are good, those that get by and those that made poor career choices. It ain't about the sign above the door... it's all about the man walking through it...

Ya done good, son... but when the truck failed that last time, I would have gone into shit deflection mode and involved the dealer that called down my diagnosis. Good luck on recovering your expenses...

"illegitimi non carborundum" (don't let the bastards grind you down).