Okay, we're making progress. This is being complicated by not knowing what the previous owner messed up.
First let me explain how the ASD relay works and what it does. That will prevent you from wasting time in the sensor circuits.
The term "automatic shutdown" by itself is confusing. They should have called it the "run" relay. This goes all the way back to the mid 1980s models. That relay is turned on by the Engine Computer, (Powertrain Control Module, or "PCM"). Normally it gets turned on two times. The first time is for just one second when you turn on the ignition switch. (You might hear the hum of the fuel pump for that one second). Next, the computer turns it on again when it sees engine rotation, (cranking or running). It knows that by the signal pulses it receives from the crankshaft position sensor and the camshaft position sensor. On models from somewhere around the early 2000s all the way back, both signals are required for the computer to turn the ASD relay on. In later models, the engine would continue to run if one sensor failed, but once stopped, the engine would not restart on just the one signal. I'm told in still later years the engine would start and run on just one working sensor in a back-up mode.
When you look at a new camshaft or crankshaft position sensor, if you see it has an oval-shaped bolt hole for mounting it, or a "U"-shaped slot, that design is adjustable for how far it is stuffed into the engine. That air gap is critical. To set that gap, new sensors come with a thick paper spacer glued to the end, or a thin plastic rib is molded onto the end of it. The paper spacer will slide off and be lost the first time the engine is cranked. The thin plastic rib can wear down a little. If you remove, then reuse one of these sensors, you can get a new paper spacer from the dealer's parts department. They only cost about a quarter, but I used to cut them in half to get two repairs out of one part. That saved one customer 25 cents! If you reinstall a sensor with the plastic rib, you're supposed to cut off the remaining part of the rib, then use one of those paper spacers. One mistake to be aware of here is if that paper spacer is required but not used, it is possible to push the sensor in too far where it can be hit by the teeth on the ring gear on the transmission. That will break the sensor.
If one or both of your sensors have a round mounting hole or the mounting ear hangs off to the side, those have the depth set automatically and there is no adjustment and no need for a paper spacer.
When the ASD relay gets turned on, it sends current to a number of places including the ignition coil(s), injectors, oxygen sensor heaters, alternator field, and fuel pump or pump relay, depending on model and year. If your truck uses a separate fuel pump relay, you can bypass it to listen for the hum of the pump by again, jumping terminals 30 and 87 in its socket. It sounds like that's what you did. Even though the fuel pump is running, you still need the ASD relay to turn on so you can power up the injectors and ignition coils. Then, even if you jump the ASD relay too, you still need the signal pulses from the crankshaft and camshaft position sensors for the computer to know when to fire each injector and coil. The bottom line is if one of those sensor signals is missing, you can jump a relay to allow testing in that circuit without having to crank the engine, but the engine isn't going to run.
Everything depends on those two sensor signals, so that's what we have to concentrate on once the cranking issue is solved. There's two ways to approach this. The less-desirable way is by reading the diagnostic fault codes in the Engine Computer. One problem here is for those sensors, it can take quite a bit of time for the computer to recognize one is missing and to set a fault code for it. Any codes that were in the computer got erased when the battery was disconnected / replaced. Any codes for intermittent defects not currently occurring also get self-erased after 50 engine starts. Next, simply cranking the engine may not be enough time to set a fault code for these sensors. It often takes coasting to a stop with a stalled engine for the missing signal to be detected. For this reason, never assume those sensors are okay just because there's no fault code set for them.
The better way to check for these signals is to use a scanner to view "live data" and see what the computer is seeing and responding to. I have a Chrysler DRB3, (diagnostic readout box, version 3), for all of my older vehicles. Those went obsolete beginning with the 2004 Dakota / Durango, and on all Jeep models by 2008, as I recall. Depending on the year this scanner was built, they will work on models back to 1996 or 1998. With an extra, plug-in card, (in a slot on the bottom), it will work on models back to 1994 with the "Supercard 2" or on models back to 1983 with the "Supercard 1). The Supercard 2 also allows it to do emissions-related testing on any car brand sold in the U.S. starting with 1996 models. For that reason, a lot of independent repair shops bought them. Since they're obsolete now and there are much better alternatives, you can find these on eBay, but they still bring big bucks. When these were new, they were available from the manufacturer on their web site for $6200.00 for a rather extensive kit, but that didn't include any of the extra cards that were available. The last time I looked, they were going for around $2000.00 on eBay.
A better value is the Snapon Solus Edge. I got mine on eBay for my newer vehicles. The problem with these is the annual updates are extremely expensive, so a lot of shops just keep one updated and let their others become outdated, then they buy a new one. At roughly $4000.00 that's cheaper than spending $1000.00 per year for four years and ending up with an up-to-date four-year-old scanner. You also have to pay extra for Asian import coverage and more again for European import coverage. One of those includes Harley Davidson. I bought my used Solus Edge from a reseller on eBay in 2018 updated to that time, and I've never updated it beyond that. My two newest vehicles are 2014 models, a I plan to never buy anything newer.
A still better value to consider is a scanner from Autel. One of our other experts recommended it so I looked into it and bought one, also on eBay. For $1300.00 I can program keys and modules, and I have full coverage for every car brand in the world. That's right, I can diagnose a Russian car if they can drive it over to me!
Getting back to the DRB3 and the cam and crank sensors, on the live data screen, you scroll down to the sensors and both will be listed with a "No" or "Present". Both will show "No' at first, then you want to see them switch to "Present" as soon as you start cranking the engine. If one of them stays on "No", that is the circuit that needs to be diagnosed, regardless if a fault code for it is set or not. The aftermarket scanners display the same information, but I don't remember the exact wording.
A scanner is a good value if you're going to have more use for it, and if you've never used one, you're in for some fun as there's so much you can see and a real lot of stuff you can command computers to do, such as turn relays on and off. The least expensive route is to get a simple code reader. Those go for around $30.00 to maybe $80.00. The biggest problem with these is while almost all of them now also display sensor data, the screens take a painfully long time to update, as in two to three seconds. That's way more than enough time to miss little glitches when you're manipulating, say, a throttle position sensor, and watching for a dropout. You'll never see that dropout unless it lasts long enough.
Most scanners have a recording capability where you can replay a few seconds of data very slowly to watch for any elusive glitches.
All of this scanner information is pointless if all you want to do is read fault codes, and only in the Engine Computer. Chrysler made doing that yourself much easier than any other manufacturer. Simply turn the ignition switch from "off" to "run" three times within five seconds without cranking the engine. Leave it in "run" then watch the code numbers appear in the odometer display. (On 1995 and older models you count the flashes of the Check Engine light to read the codes). Either way, you can go here:
https://2carpros.com/trouble_codes/obd2/
to see the definitions, or I can interpret them for you. By the way, 1996 is when they started with the OBD2 emissions system, (on-board diagnostics, version 2), which included the three-digit fault codes. That was a standardized computer language used on all vehicles sold in the U.S. starting with '96 models. For 1995 and older models, every manufacturer had their own computer systems with nothing interchanging. You have to watch that any aftermarket scanner is capable of talking to the computers on your vehicle. On the page I just listed with the fault code definitions, way at the top it lets you "switch to OBD1 codes" if you're diagnosing a '95 or older model. Each brand is listed separately and each one includes instructions on how to get the codes. Chrysler is the easiest, by far. Ford is one of the most complicated and miserable.
When it comes to the crankshaft and camshaft position sensors, there's two basic designs. Older vehicles typically used two-wire sensors. Those were nothing more than a long, thin wire wrapped around a magnet. On some cars, accidentally switching those two wires had no effect on engine operation. On some, it changed slightly when an ignition coil or injector fired. Later models almost always use three-wire sensors. Those have the same coil of wire around a magnet, but to be more precise in their timing, they generate rather weak signals. Therefore, they build in an amplifier circuit that needs a ground and a power supply of 5, 8, 10, or 12 volts. Chrysler usually uses a very carefully regulated 5.0 volt supply. None of these wires can be switched, so if a previous owner was in there doing some wiring, that's a good place to start. If you see splices or other evidence of someone being in there, I can find the connector diagrams and post them for you. Those include the wire colors for each terminal.
All of this wondrous information applies after we get the starting system working. At this point, don't waste your time testing other sensors. We'll revisit the cam and crank sensors if necessary, and all but one of the other sensors won't prevent the engine from running. If you have a defective coolant temperature sensor, for example, or throttle position sensor, or intake air temperature sensor, the engine will run with those failures, then the Engine Computer will detect those defects and set a fault code to let us know where to start the diagnosis. It's also important to be aware that fault codes never, ever say to replace a sensor. When a sensor or other parts is referenced in a fault code, it is actually the cause of that code only about half of the time. First, we have to rule out wiring and connector terminal problems, and mechanical problems associated with that part. This is why we read way too often that someone "replaced a sensor three times and the same code still sets". It isn't a bad sensor. It's usually one of the wires going to it.
By the way, once we have the starting system working properly, I'll have you start a new question for the cam and crank sensors or any other, unrelated problems. That's done for the cataloging process. With multiple topics covered in one question, someone researching a similar problem will never see our newer conversation as it won't show up on any list. Also, this has become a private conversation between the two of us. As such, none of the other experts are likely to see the new topic or have a chance to reply. Believe it or not, sometimes I'm not the best person to continue with the new topic. My specialties are electrical, suspension and alignment, and brakes. Outside of those areas, I usually defer to people smarter than me!
So if I read this right, you have the starter working now, but you had to bypass the neutral safety switch? If I have that right, that switch is suspect. Failures are not so common that I wouldn't trust a used one from a salvage yard, but be aware there is an aluminum gasket on them that should be replaced too. If you get a new switch from the dealer, they will have that gasket too. Don't try to seal the switch with Teflon tape as that will insulate the ground circuit for the starter part of the switch, then you'll have the same problem.
Let me know when you're ready for a pat on the back.
Aug 19, 2026 at 4:27 PM
