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3.0 V6, CVT automatic, PAT system, and an intox-a-lock breathalyzer. We’ve already worn out blow job jokes while working on this car. Please don’t bother with any more of said jokes. The way the car behaves is that I can get a clanging/clanking crank-no start or I can also get a no crank-no start. I’ve got some pics and diagrams to share with you to help out.
I started with voltmeter testing that was inconclusive while it was clanging. The starter relay was swapped with two other nearby relays with no change in behavior.
When it went to no crank condition, the following tests were conclusive. I ruled out an ignition switch fault by reason of starter relay voltage. The starter relay is power side switched. Both the 85 and 86 pins have full battery voltage with key in crank position. Said starter relay feeds a pink wire going to the PCM. That pink wire also showed full battery voltage with key in crank position.
At this point, I condemn the PCM for not grounding the relay. I follow up with one more test by back probing a jumper wire from the pink wire directly at the PCM and send it straight back to battery negative. The starter now cranks flawlessly every time. The pink wire pulls all the way down to ground as well.
A used donor PCM is installed, reflashed with the original PCM’s software, and PATS keys are relearned using Ford IDS software. The car starts on the first try, but a clang is heard just as it starts. I shut the engine off and attempt multiple restarts and I’m back to clanging crank-no starts.
Originally, I never thought to look for an anti theft fault with a scan tool. There is an indicator light for it in the cluster and it never turned on past the bulb check. It did flash during key relearn, but never during any attempt to crank the starter once I started paying attention. I have yet to look at live data for the anti theft on a scan tool either.
In spite of the risk of destroying the starter or the flywheel, I decided to pull out a scope and look at that pink wire on a trace. I also scoped the solenoid wire too. I pulled it off before I took this screen shot, but all it shows is that the solenoid is reacting appropriately when the starter relay is being grounded. The yellow trace represents the pink control wire directly at the PCM. Now I can at least explain that the clanging is through no fault of the starter. This trace should be flat lining at zero with the key in crank position.
I did finally test all four PCM grounds, at this point, and they were clean at 10 mV while cranking.
I ran out of time for testing and I won’t be able to get back on the car for a couple days yet. When I do get back to the car, I may scope that 85 terminal of the starter relay, but I think I’d be a dog chasing my tail in that.
Of course, I’m suspicious about what that breathalyzer could be doing wrong. But, I have no circuit information whatsoever on that contraption yet. It requires special permission before I can remove it anyway. If somebody has experience installing these intox-a-locks, I’d love your input.
The only other thing I’m wondering about is the #7 pin labeled SMR on the wiring diagram. The factory connector chart calls it “VOLTAGE SUPPLIED IN START (OVERLOAD PROTECTED)”. Does anybody know something more specific about what it’s supplying voltage to or how could this be affecting the starting circuit?
Thanks!
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Whats bothering me is the PATs system is not coming into play. No flashing or anything.
I don’t have any experience with the intox analyzer. what is the analyzer doing when trying
to start? doesn’t that have to be proven first to release start?It looks like pin 7 should be system voltage. Are you getting a steady voltage out of the SJB during cranking? It looks like whatever is supposed to be triggering the relay isn’t holding it.
It might be worth looking into where the interlock is tied in. Locally we have mandatory immobilizers on cars with insufficient factory systems. They time them into the starter trigger wire. So at the very least you should be able to send 12V to the starter solenoid and it should start with the key on. A co-worker had one of the immobilizers and the soldering around the relay separated causing the system to not work.
I would see if you could temporarily remove the interlock, or refer it to whomever installed it to diagnose their component. In my not expansive experience, if there’s something added on, it’s usually responsible for a fault. A co-worker had a van that was completely immobilized after a soldered connection broke on a command start at the B-CAN line.
[quote=”college man” post=158793]Whats bothering me is the PATs system is not coming into play. No flashing or anything.
I don’t have any experience with the intox analyzer. what is the analyzer doing when trying
to start? doesn’t that have to be proven first to release start?[/quote]
The PATS just isn’t an issue. As it turns out, neither is the breathalyzer thing. At least not electronically. There’s probably upwards of a dozen wires entangled in that mess. But there were only three that concerned me.One needs to tap into battery voltage circuit that’s constant with key on. I didn’t bother to understand why, this car is kicking my ass enough as is. I just made sure that there was battery voltage at that circuit. They used these weird capped wire taps to essentially splice in. The other two wires are run in series with the wire that controls the starter relay.
Oh, and yes you do have to pass the breathalyzer to start the car. With the particular version I’m working with, it’s not enough to blow clean just to start the car. It does random rolling rechecks along the way and I get locked out of the start circuit for two minutes if I don’t blow in time. It’ll set off the horns and flashers too. It does an awesome job of disrupting your work flow and your train of thought.
[quote=”DaFirnz” post=158809]It looks like pin 7 should be system voltage. Are you getting a steady voltage out of the SJB during cranking? It looks like whatever is supposed to be triggering the relay isn’t holding it.
It might be worth looking into where the interlock is tied in. Locally we have mandatory immobilizers on cars with insufficient factory systems. They time them into the starter trigger wire. So at the very least you should be able to send 12V to the starter solenoid and it should start with the key on. A co-worker had one of the immobilizers and the soldering around the relay separated causing the system to not work.
I would see if you could temporarily remove the interlock, or refer it to whomever installed it to diagnose their component. In my not expansive experience, if there’s something added on, it’s usually responsible for a fault. A co-worker had a van that was completely immobilized after a soldered connection broke on a command start at the B-CAN line.[/quote]
I did indeed take some time to test pin 7 and, while I’m still not entirely sure what it does, it’s providing battery voltage to the PCM during cranking as it should.I did spend some time on interlock testing and it wasn’t what I expected it to be. I know you’re talking about the breathalyzer, but the car has its own interlocks too. The shift interlock circuits on this car only do two things. They lock the shifter in park until you hit the brake pedal and it locks the ignition key to the ignition cylinder while the key is on. There is no correlation between these and the starting circuit.
Today, I started learning more about that Ford IDS scan tool. I hated it at first, but it’s growing on me. It didn’t solve any problems so much, but it did eventually help me rule out a few things. Finding the information I need has always been the bane of any car I have to diagnose before I can repair. Finding anything in IDS started out painfully slow. But once you start to find anything, you start to find everything. If you’re new to the IDS, go to the data logger option. You’ll get more than you can stand in PID data. You don’t necessarily get it all at once though.
In my own hunt, I found a starter relay PID that will tell you if the relay is enabled or disabled. It turns out that the PCM was trying to disable the starting circuit, albeit I still had no clue or other nearby info to give me a reason why.
I finally found shift position, or transmission range PIDs too. I found one PID called TR, and the other TR_ALW or something to that affect. The TR stood for transmission range and basically that’s the one that told me what gear the transmission was in. This was awesome and terrible at the same time. It showed me that the TCM actually always knew that I was in park every time I was trying to crank the engine. The other PID was basically a yes/no PID that states whether or not the signal from the TCM was allowing the PCM to ground the starter relay. It always showed me yes while I was looking for it though. I still was neck deep in clanging cranking though. It would have been nice to see the starter relay PID the same time as the TR PIDs.
I never paid much attention to the LB/YE wire between the PCM and the TCM because it was another one of those what the hell is it circuits I couldn’t find a plain English explanation for. It turns out, it’s the trans range input wire to the PCM. That’s the wire that should let the PCM know it’s ok to ground the starter relay. I voltage drop tested that wire KOEO and I get battery voltage at the PCM end and only 2.6ish volts at the TCM end. I shifted out of park a few times to see how the circuit would behave and it eventually dropped to .12 volts at the TCM. I almost mistook it for a signal voltage at the TCM end, but the voltage should be the same at both ends of the circuit if that were true. I tried a jumper wire, but it didn’t change the voltage at either end so I think I just didn’t make a good contact at the TCM end. When I disconnected the harness at the TCM end, the voltage would raise to 10.65 volts.
This sparked a little debate at work and one guy thinks it’s an issue with bad pin contact. But I’m still stuck on the idea I’ve got a high resistance problem in that wire. I’m sure a pin contact fault is a viable problem, but as long as I’m back probing on the pin, I should still have the same voltage on either end of the wire since it seems that the PCM is supplying the voltage.
Whatcha think of that?
Interesting read.
If you don’t have access to Idnetifix, you should really have your boss look into it. It has all the manuals in it, but it has the best tech level information searching I’ve seen yet and for a fee, you can call in and talk to someone about it. They have access to some next level information and are pretty good about knowing what they are doing.
Speaking of which, I still have my old employers password…..
Oh, and by interlock I was referring to the breathalyzer.
I’m ashamed to say I did call Identifix already. It’s not to say they didn’t help, but had I known more about that signal wire up front, I would have never needed to call them. I had trouble finding a diagram that identified the wiring to and from the TCM well enough and the guy from Identifix gave me the detail on that LB/YE wire. I should have tried a little harder to find a diagram or some info on that signal circuit.
At any rate, I tried installing another jumper wire this morning. But this time I just pierced the wire at the TCM end of the circuit and I got my battery voltage back on both ends of the circuit. I cut and spliced new wire in from end to end and now that stupid car starts up every time. I looked at the car and said, “It’s your turn to blow me.” The car just sat there and I’m still very disappointed.
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