2001 Dodge Grand Caravan wiring problem

How did you find pulses to the coils and injectors? The same sensors that time those pulses turn on the automatic shutdown relay that sends voltage to those items. My guess is you're finding those pulses while cranking the engine but checking the voltage while not cranking. Does that sound right?

The Engine Computer turns on the automatic shutdown (ASD) relay for one second after you turn on the ignition switch, then it turns it back off. You might hear the fuel pump run for that one second. There will also be battery voltage on the dark green / orange wire at the coils, injectors, and small wires on the back of the alternator. That voltage will only return when pulses are received from the crankshaft position sensor and camshaft position sensor. That means you must test for that voltage during engine cranking.

If that voltage is missing during cranking, suspect those two sensors. There will usually be a diagnostic fault code stored in the Engine Computer so it is important to not disconnect the battery or that valuable information will be lost. Reading those codes is the best place to start. They will lead you to the circuit or system with the problem, not necessarily the defective part.

If you DO find voltage on the dark green / orange wire during cranking, is is much more likely the fuel pump isn't starting up. You can prove that by testing the fuel pressure. If the pump is dead, it will often start up if you bang on the bottom of the fuel tank while a helper cranks the engine.

Okay, just when I had everything memorized, they changed things, ... Again! The closest service manual I have is a 2002 which shows different wire colors than the older models. I sent you looking for a dark green / orange wire but instead you might have a brown / white wire feeding the injectors and coil pack.

The fuel pump has its own relay so it would appear both the ASD and pump relays are not turning on or the common power feed is missing. For starters, measure the voltage on fuses 16 (25 amp) and 17 (20 amp). That voltage comes right off the battery.

If it's there, remove the ASD or pump relay and check for voltage on terminal 87. If you have it there, use a piece of wire or stretched out paper clip to jump terminals 30 and 87 together in the socket. The pump should run or you should have voltage at the coil pack and injectors. If you do, that means those relays aren't being turned on by the Engine Computer. You might be able to feel them click but I prefer to pop the cover off a relay, reinstall it that way, then watch the contact when a helper turns on the ignition switch.

Holler back with the results of your testing. In particular, do those relays turn on at all? If they do not, check for voltage on terminal 86 in the relay socket when the ignition switch is in the "run" position. For a more accurate test, it is best to leave at least one of the relays installed so there is a load on the circuit.

Woops; sorry, I overlooked your comment that the relays turn on. Check for voltage on those two fuses.

Clarify this:

"there was a relay missing a ASD relay I put one in it now it has 11.4 volts to the coil, injectors and alt. Only when cranking"

"but nether of them are working when key is on or cranking"

The way I'm reading this, you're saying two different things. If those relays are not turning on during cranking, the first suspect is the crankshaft position sensor or the camshaft position sensor. One thing that might help is checking for diagnostic fault codes which can point to the circuit with the problem. Chrysler makes that very easy. Do you know how to read them by cycling the ignition switch three times within five seconds? The codes should read out in the odometer display. There should be at least one related to the missing ASD relay. Hopefully there will be more.

It's the pulses from those two sensors that tell the computer to turn on the ASD relay. On newer models that will occur and the engine will still run if the cam sensor fails but the crank sensor has to work. On older models both sensors have to work for the relay to turn on. I'm not sure where a 2001 falls in there.

Be aware too that if you remove the crank sensor, it requires a paper spacer to be stuck to the end of it when reinstalling it to set the air gap. If you just shove it in all the way and pull it back a little, you'll have no idea what the gap is. I got stung by doing that once. If you stuff it in all the way without a spacer, it can hit the ring on the flex plate and break.

In your first sentence the automatic shutdown relay is working properly. In your second sentence you said both are not working at all. Last, you said the fuel pump relay is never turning on. That can't be good! And that's where we should start.

Grab a test light, (or a digital voltmeter), remove the fuel pump relay, and test for voltage on terminal 86. The voltage comes right off the ignition switch so that will have to be in the "run" position.

Next, move the ground clip for the test light to the battery positive post and probe terminal 85. We're testing for a ground circuit now. The light should light up for one second when you turn the ignition switch on and again during cranking.

One of those two circuits has to be not working. In fact, your code 1282 is for "Fuel Pump Relay Control Circuit". That's terminal 85 but the code doesn't specify if it detected that due to missing supply voltage on terminal 86 or if there is no current flow through the circuitry in the computer. In other words, did it set the code for a problem within the computer itself, a problem in the rest of the van's circuitry, or did it set simply from you pulling the relay out while the ignition switch was on? I don't know if removing the relay will set that code right away or if other conditions must also be present.

Now, here's something else that might be related. Code 123 is for the throttle position sensor signal voltage too high. 118 is for coolant temperature sensor voltage too high, and 1598 is for the air conditioning pressure sensor voltage too high. The only way any of those sensors can read too high is if there is a physical break inside it or the ground wire has a break. Now, here's where it gets interesting, and confusing. All three of those sensors share a common ground wire, so it's extremely likely that wire is open. It is very rare to have an open sensor, and it's REALLY REALLY unlikely three of them are open at the same time, unless those codes were set because they were unplugged while the ignition switch was on. That might be all that happened because there are many other sensors that also share that common ground wire and they didn't set codes. If you unplugged those three sensors, you can disregard this entire paragraph. If you didn't unplug 'em, check for voltage on dark blue / dark green wire on the throttle position sensor. That should be the easiest one to access. Normal voltage is 0.2 volts. If you find 5.0 volts, (ignition switch on), there is a break in that circuit that we have to narrow down.

To add to this, if that wire really is broken, there is a specific set of conditions that must be met for a fault code to set and one of them is that certain other codes are not already in memory. That is because the computer often compares one to another and if it knows it can't believe or trust one sensor's reading, it can't compare other sensors to it.

See where these tests take you, then holler back with what you find.

Dandy. We're making progress. 87 is the 12 volt supply to the relay contact. He's good. 86 needs 12 volts from the ignition switch. He's missing and must be checked further. As for 85, the ground circuit you're testing is switched on and off inside the Engine Computer. The test light just takes the place of the relay's coil, but the clip on the battery positive post is taking the place of the missing 12 volts from the ignition switch. That is probably feeding through the computer circuitry to the circuits for some of the other relays. That probably is not a very informative test, especially since we already know terminal 86 is dead.

I think you're going to find a defective ignition switch. You can double-check that you have voltage on the feed fuse # 23, but that one also feeds the starter relay through a different set of contacts in the switch. Since it cranks, that circuit must be good. You can verify that at the switch connector after you remove the trim covers under the steering wheel. 12 volts comes in on the 20 gauge light blue / red wire and goes out on the 20 gauge pink / white wire when the switch is in the "run" or "crank" position. If you have it on the first one but not on the second one, first check the connector for signs of melting and overheated terminals. That would seem strange. Overheated terminals are rather common but not on that circuit because it's a relatively low current circuit. That happens more often to a different circuit that feeds the power windows, radio, and heater fan and it acts up more for people who use the heater fan on the highest setting often. Regardless, if the switch is the problem, use a piece of wire to jump the light blue / red wire to the pink / white wire, then try to start it. Oh, don't forget to stick the relays back in first.

If you DO find 12 volts on the pink / white wire when the ignition switch is in the "run" position, there has to be a break in that wire between the switch and fuse box. We'll continue narrowing it down if it comes to that.

What voltages did you find on the two wires at the ignition switch?

Okay, you gots 12.15 volts on the pink / white at the ignition switch but 0 volts at terminal 86 in the relay socket. Unless your '01 is different than the diagram in my '02 book, all that's in between those two points is that wire. Double check for voltage at terminal 86 with the ignition switch on. If it's really missing, there has to be a break in that wire.

Check for voltage on terminal 85 just for fun. There was a mistake in one of my service manuals a few months ago and they showed 85 and 86 switched around.

Okay, 85 and 86 are backwards according to my book. Well, wait a minute. How are you determining 86 is ground? Describe your test procedure.

You might want recheck for voltage on 85 with the fuel pump relay AND the ASD relay removed. Even though the ground circuits are on different pins in the computer connector, one might be back-feeding to the other relay socket.

If you still find voltage on 85, reinstall all the relays and add a piece of wire to the ASD relay terminal 86 so you can access it with the relays in place. Now, after the ignition switch has been on for more than a second, you should find 12 volts on 86. That voltage is coming from 85 and through the relay's coil. During cranking, the computer is supposed to ground that terminal to turn on the relay so you should see 0 volts then.

Just so we don't burn something up in the next step, use another piece of wire in terminal 85 so you can check the voltage there too.

I think before I go on, holler back with the answers to my questions so I can be more confident in the terminal numbers I'm using.

Sorry for the delay. High winds, trees down, power out, 'puter dead until a few minutes ago.

You gotta put some commas in the sentences. Are you saying you find no voltage to 85 AND 86 with the ignition switch on? If so, you have to have a broken wire between the switch and relay. That's the pink / white wire.

I would love to post diagrams for you but I have never been able to get into the web sites we have access to. The best I can do quickly is to describe the circuits and wire colors. If you need more than that, I can make some line drawings in MS Word, then convert them to JPEGS that I can post here.