cranks if I jump the relay but no spark after major engine work?

2005 JEEP GRAND CHEROKEE LAREDO
214,000 MILES • 4.7L • V8 • 4WD • AUTOMATIC
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BILLY WEBSTER
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So, I replaced the PCM and changed the valves and head gaskets. got ti back together and it started turning over and started when i gave it some gas but stalled out after a second. I only tried it a couple of times then let it sit until the next day. When I attempted to start it, I turned the key and the lights all worked and i heard the fuel pump but that's it. I think there is a click from the relay but it's hard for me to hear from the cab. The battery is charged and the starter cranks when I jump it at the relay. I tried pulling a spark plug out and it's not sparking when I manually crank the starter. I'm guessing it's the PCM again? The crankshaft positioning sensor seems to be working I pulled it out and ran metal in front of it. it seemed to be less responsive than I would expect it to be and the same goes for the camshaft position sensor.
Oct 28, 2023 at 8:15 AM
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JACOBANDNICKOLAS
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Hi,

It sounds like you have more than one issue. There are two fuses that can affect the ignition coils. (Fuse 6 and fuse 16) both are in the power distribution center under the hood. Additionally, there is a relay called the automatic shutdown (ASD) relay. If that isn't operating correctly, you won't have power to the fuel injectors and pump, so it sounds like it is. That leaves fuse 16 specifically.

Here is what I want you to try. At each coil, there will be a red wire with a tan tracer. With the key on, that wire should have power. Check that first. If it doesn't, check fuse 16 in the PDC. When you check the fuse, make sure there is power to it.

I attached the schematic below so that you have a reference. The first two pics are of the ignition system. The second two are the starter circuit. If the PCM isn't providing a ground path via pin 85 on the relay, the starter won't engage. Additionally, pin 86 is the power supply from the PCM to the relay. Both pins 85 and 86 need checked to see if we have what is needed. Note that both will require the key to be in the start position, so you will need a helper.

Let me know if this helps or if you have questions.

Take care,

Joe

See pics below.
Oct 28, 2023 at 9:23 PM
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BILLY WEBSTER
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Okay, sorry I just finally had time to do this, and it appears as if the wire is getting power when I hit the jumper switch, but my battery is drained until my stepdad gets here to charge it. when I jumped it, I heard a relay clicking like crazy if that means anything and almost thought I heard it spark and wanted to catch in its futile attempt at powering the starter. I'll be back hopefully tonight and let you know how it goes with power.
Nov 4, 2023 at 5:42 PM
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BILLY WEBSTER
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I also checked the pink and orange wire I think goes to or from the PCM and it is getting power.
Nov 4, 2023 at 5:43 PM
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BILLY WEBSTER
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at the starter relay**
Nov 4, 2023 at 5:43 PM
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JACOBANDNICKOLAS
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Hi,

Thanks for the update. When you say jumper switch, what are you referring to? Also, if you hear a relay clicking, see if you can determine which one it is. You should be able to feel a vibration if you place a finger on the relay.

Let me know.

Joe
Nov 4, 2023 at 8:26 PM
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BILLY WEBSTER
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Okay, so, I charged the battery and the coils all had power when I initially turned the key to crank. They don't get power again until I turn the key off and do it again. The number switch is just a hand switch connected to the two points on the starter to bypass the relay to crank it. I want to add I just realized my sunroof and side windows don't work nor do my headlights or emergency lights but with the relay for my running lights in the running lights are on any time the batter is connected and same with the relay for the high radiator fan. I noticed my fuses that are all in a row that are 10a are very corroded I cleaned them as best I could and tomorrow I am going to get the proper cleaning supplies to get them all cleaned up.
Nov 4, 2023 at 9:56 PM
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BILLY WEBSTER
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Also, relay for the starter showing power when key is turned as well.
Nov 4, 2023 at 9:58 PM
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JACOBANDNICKOLAS
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Hi,

You can have power at the relay, but for it to actuate, there needs to be a ground path supplied to the primary side of the relay. It will be either pin 85 or 86 on the relay.

Here is a link that explains how to test a relay and its circuit:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know about the fuses. Based on your last description (power to coils), it may have something to do with the ignition switch. You should have power at all times when the key is in the start or run position. Also, the new findings regarding power loss is interesting. Let me know if cleaning things up makes a difference.

Take care,

Joe

Nov 4, 2023 at 11:03 PM
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BILLY WEBSTER
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okay, so the clicking is not the starter relay it's the HVAC relay and when I tested the relays for the running lights and radiator fan, they had 2 on for power and two off but when I tested ground they had 2 on one off and 1 reading like .05. The relay is getting power for the starter but it's not clicking when I turn the key. '
Nov 8, 2023 at 11:38 AM
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BILLY WEBSTER
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I am also hearing a click from inside the dashboard.
Nov 8, 2023 at 12:00 PM
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JACOBANDNICKOLAS
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Hi,

If the starter relay doesn't click when it's in the start position and it does have two power supplies (two different pins) either the primary side isn't getting a ground path, the relay is bad, or the starter motor is bad, or isn't getting power.

Try one of these tests. At the starter motor is a yellow wire with a gray tracer. Have a helper turn the key to the start position while you check if the yellow/gray has power. It should only have power in the crank position. Also, the heavier gauge red wire has battery voltage at all times, so confirm that is the case.

Or remove the starter relay. You indicated it is getting power. Each of the 4 pins is numbered on the relay. Pins 85 and 86 are for the primary side. Confirm one of them has power. If it does, attach the alligator clip of the test light to the battery positive and probe the other connector. Have someone turn the key to the start position. In that position, your test light should turn on. If that doesn't happen, that is why the relay won't actuate.

Let me know what you find.

Joe

Nov 8, 2023 at 6:02 PM
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BILLY WEBSTER
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so, you said 85 and 86 should have power to one constant and the other one should ger power when its cranked? the red and yellow seem to be functioning right teres a constant and the other lights up when cranked.
Nov 9, 2023 at 1:43 PM
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BILLY WEBSTER
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85 and 86 are the two end ones in the row that has 3 in it, correct?
Nov 9, 2023 at 1:58 PM
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BILLY WEBSTER
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if so, I am not getting power when I test it with the light but it seems to have voltage when touch the meter to it.
Nov 9, 2023 at 1:59 PM
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BILLY WEBSTER
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i take that back yellow wire not lighting up when cranked.
Nov 9, 2023 at 2:45 PM
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JACOBANDNICKOLAS
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Hi,

It should have a connector schematic on the relay itself. As far as the yellow wire, if there is no power, check fuse 10 in the power distribution center under the hood. Also, check it for power. See pic below for the fuse location.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Keep in mind, the yellow/gray wire will only have power if the relay is working, and the key is in the start position. I'm assuming there is power from the ignition switch to pin 86 when in the start position and ground at pin 85 in the start position.

Let me know what you find. Also, I realize giving directions online are not the easiest to follow. Please let me know if you have questions or if I'm not making sense. LOL

Take care,

Joe

See pic below.
Nov 9, 2023 at 8:26 PM
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BILLY WEBSTER
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okay, so, the yellow wire is 87 on the relay so to test that I have to have the relay connected? also, what am I looking for at the ignition switch? As in the wires that would be involved In my situation, also is there a way to test the skimm?
Nov 9, 2023 at 8:57 PM
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JACOBANDNICKOLAS
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Hi,

To check pin 87, yes it needs to be connected. Use a thin paper clip or wire and push it in with the relay on pin 87.

As far as the ignition switch is concerned, don't worry about the switch at this point. When the key is in the start position, pin 86 should get power. If it does but pin 87 doesn't, then I need you to check pin 85 for continuity to ground when the key is in the start position.

The easiest way to check for a ground path at pin 85 is this. Take the alligator clip end of a test light and connect it to the battery positive. Probe pin 85 with the test light. When the key is placed in the start position, the test light should turn on if a ground is provided.

As for the Skim/Skreem circuits, we need to scan for B codes/can-bus system. Otherwise, if there is a problem within that circuit, it will be nothing but luck if we find it. A code such as B1A25 would be an example of a possibility.

Let me know.

Joe
Nov 9, 2023 at 9:36 PM
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BILLY WEBSTER
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i don't have any communication.
Nov 9, 2023 at 10:46 PM
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JACOBANDNICKOLAS
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Billy,

What are you referring to when you say communication? Do you mean there is no continuity to ground?

Let me know.

Joe
Nov 10, 2023 at 7:24 PM
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BILLY WEBSTER
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no scanner communication with the dlc port.
Nov 10, 2023 at 8:35 PM
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JACOBANDNICKOLAS
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Hi,

Pin 16 in the DLC should have battery voltage at all times. Check to see if that is the case. If there is no power, check fuse 16 in the junction block. When you check the fuse, confirm there is power to and from it.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

I attached a pic of the DLC to help locate pin 16. Pic 2 below shows the fuse in the junction block.

Let me know.

Take care,

Joe

See pics below.
Nov 10, 2023 at 10:29 PM
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BILLY WEBSTER
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the pin has power.
Nov 14, 2023 at 9:56 AM
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BILLY WEBSTER
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I don't know if this helps... Not even sure if it was making that squealing noise before now..
Nov 14, 2023 at 10:18 AM
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JACOBANDNICKOLAS
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Hi,

I believe the red flashing light indicates the immobilizer is activated. Am I correct that is the light?

Joe
Nov 14, 2023 at 2:54 PM
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BILLY WEBSTER
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I'm pretty sure but I haven't found much documented on it. every other jeep light I saw had symbols not just a red light...
Nov 14, 2023 at 3:10 PM
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BILLY WEBSTER
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It's starting to add up I think because I had a similar issue after I started working in it. I changed the timing chains and when I put it back together if I remember right I was having a no-crank issue after replacing the crank and camshaft sensors and eventually the PCM at the same time I changed the head gaskets I was stoked because I hit the key and it turned over and started for a second a few times then stalled out. I figured it was old gas but the next day I went to crank it and got nothing.
Nov 14, 2023 at 3:18 PM
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JACOBANDNICKOLAS
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Hi,

I have a 09 Dakota and that light is the same as my anti-theft light. What did you do the last time this happened? Also, have you confirmed power to the PCM?

Let me know.

Joe
Nov 14, 2023 at 3:54 PM
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BILLY WEBSTER
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The last time it happened was when I replaced the PCM. How do you test the past to the PCM? I have tested the crank and camshaft sensors, and they seem to be working although not exactly statically they were acting pretty flaky, but I figured it was my battery needing to be charged at the time...
Nov 14, 2023 at 5:17 PM
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BILLY WEBSTER
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If you couldn't tell when it comes to electrical I'm not the most up the date on it... There are so many wires in this truck... A couple of the bunches are as thick as a baseball bat with them... It's maddening at times...
Nov 14, 2023 at 5:21 PM
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JACOBANDNICKOLAS
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As far as the PCM, you need to run a can-scan, but that can't be done with the DLC issue. Did you check the pins identified as ground in the DLC pic above?

Let me know.

Joe

Nov 14, 2023 at 8:35 PM
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BILLY WEBSTER
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Yeah, I had the pis on 16 and neg on 4 and 5 and it read 12 ish for each.
Nov 14, 2023 at 8:57 PM
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JACOBANDNICKOLAS
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Hi,

Double-check all connections at the PCM. If they are good, chances are the PCM is the issue. If we have power and ground where it's needed, that is my first suspect.

I wish I had a better answer.

Joe
Nov 15, 2023 at 7:12 PM
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BILLY WEBSTER
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Do you know if there's anywhere that rents out those DRB3 scanners?
Nov 15, 2023 at 9:06 PM
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JACOBANDNICKOLAS
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Hi,

Unfortunately, I don't. That is a Chrysler scan tool. I wish I had a better answer for you.

Joe
Nov 16, 2023 at 7:57 PM
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BILLY WEBSTER
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how do I tell if its the key or the module that messed up?
Dec 9, 2023 at 5:27 AM
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JACOBANDNICKOLAS
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Hi,

The easiest thing to do is check at the relay for power and a ground supply. If there is an ignition issue, you won't have power to the primary side. If it is the PCM, chances are you won't have a ground path at the relay.

Let me know.

Joe
Dec 9, 2023 at 10:32 PM
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BILLY WEBSTER
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Update- the obd2 port is not communicating with the PCM I tried to have my key reprogrammed and he couldn't do it because of this.
Dec 9, 2023 at 11:23 PM
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JACOBANDNICKOLAS
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Hi,

Check to see if there is battery voltage to pin 16 at the data link connector. If there isn't, check to see if fuse 16 in the under-hood fuse box is good. See pic below.

Let me know what you find.

Joe

See pic below.
Dec 10, 2023 at 7:18 PM