Must be connected to start connections?

Billybob · **Posted:** Tue Dec 10, 2019 1:07 pm

Jumping the starter relay out gives you good starting you say.

This jumpering of pin 30 to 87 bypasses the ignition switch, actuator pin assembly, Park sensor, Neutral sensor. Basically feeds +12 volts direct from Fuse#8 40 Amp to the starter solenoid. If the chipped key is in the ignition slot and ignition is ON then the engine should start and run.

So you must have a good +12 volts going to pin 86 of the starter relay (coil) via Fuse #28 15 Amp. Make sure that fuse is good and in clean and tight.

Then pin #85 of the starter coil is supposed to get Ground via the ECM Pin #58 of connector C2. This Ground will only appear if the ECM detects that the Jeep is in Park or Neutral.

So if there is +12 volts on pin 86 of starter relay...you need to keep your meter lead on pin 86 and move the other lead to pin 85 to check for ground. If ground is not there you need to move the lead down through connector C111 pin# 10 to check for Ground and then to the ECM pin 58 of C2 connector.

If Ground is not at ECM pin 58 then the Park and/or the Neutral interlocks are not working...try start it in Park. :wink:

Mountainman · **Posted:** Tue Dec 10, 2019 6:01 pm

Ok, the 3.4v is some weird residual voltage that's there when the ignition is on. I do have 12v. All grounds, fuses, relays are good. Second key same thing, neutral or park, same thing.

This where it gets strange (or obvious); I am getting the same condition jumping the relay. Something changed at some point. I know these batteries start other jeeps, but this engine is rebuilt and pretty dang tight (not too tight). But it's definitely commanding a lot more out of the batteries. So, I linked two, same condition.
I though it was a strait shot, so Seems that I'm down to a bad starter solenoid wire. Ohms out good, but time to check it energized. Could be 3 batteries that cant handle 5he load also. They are all older...

flash7210 · **Posted:** Tue Dec 10, 2019 6:19 pm

Now we are getting somewhere.
Let’s hope this isn’t the case, but...

If the cylinders have water in them, it would be hard to crank and definitely have a hard time starting.

Pull the glow plugs. See how it cranks. Look for water shooting out.

Mountainman · **Posted:** Tue Dec 10, 2019 7:59 pm

flash7210 wrote:

Now we are getting somewhere.
Let’s hope this isn’t the case, but...

If the cylinders have water in them, it would be hard to crank and definitely have a hard time starting.

Pull the glow plugs. See how it cranks. Look for water shooting out.

Luckily I haven't added any coolant yet, but it's impressive how fast this new engine takes an ok battery under 12v. It's looking like that's the problem. I jumped straight to the starter solenoid, and same thing. Better charge on the battery, and I got a 5-6 second crank and a little fire! Charging up two batteries now. If it doesn't like that, I'll pull the oddesy out of my baby, but the old style sasquatch tray lid is a bit challenging to reinstall, and I hate risking my super expensive battery.
Seems like i likely have a drain somewhere. I'll unplug everything i can to save a little juice.

Mountainman · **Posted:** Tue Dec 10, 2019 9:53 pm

A little more background to consider. The previous engine knocked a nice hole through the block with #4 rod. I wonder if any of the big plugs on the passenger side fender could cause this, or if any two of them are keyed the same. I know it wouldnt make any sense, but look at the engine harness! I never mess with those plugs, but the PO took it all apart, and I managed to get them clicked back together...

Would it make any sense if the cat was plugged? 45 degree open garage isnt helping, but too much smoke with oil soaked pistons to have it closed.

Billybob · **Posted:** Wed Dec 11, 2019 5:10 am

Are you still getting the residual voltage of 3.4 volts on pin #86 of the starter relay when ignition is completely OFF? You can measure it both sides of fuse #28. This should not be there...could be causing current draw.

What voltage do you get on the starter motor (thick red wire) while turning engine over?
You sure the Negative Battery Cable going to chassis is clean and tight both ends and the Grounding strap grounding the engine to the chassis is clean and tight both ends?
You can expect some voltage drop at the starter motor as it does draw a lot of current but not too much drop!

Connections on the solenoid/starter motor must also be clean and tight.

The Wiring Section 8W at the end of the Index Page gives physical locations of most of the connectors, color of the connectors and color of the wires in the connectors so that should help to check if all connectors are in the correct places. The physical layout of the connectors for the Diesel starts at page 8W-91-31. :wink:

Mountainman · **Posted:** Wed Dec 11, 2019 3:09 pm

Billybob wrote:

Are you still getting the residual voltage of 3.4 volts on pin #86 of the starter relay when ignition is completely OFF? You can measure it both sides of fuse #28. This should not be there...could be causing current draw.

What voltage do you get on the starter motor (thick red wire) while turning engine over?
You sure the Negative Battery Cable going to chassis is clean and tight both ends and the Grounding strap grounding the engine to the chassis is clean and tight both ends?
You can expect some voltage drop at the starter motor as it does draw a lot of current but not too much drop!

Connections on the solenoid/starter motor must also be clean and tight.

The Wiring Section 8W at the end of the Index Page gives physical locations of most of the connectors, color of the connectors and color of the wires in the connectors so that should help to check if all connectors are in the correct places. The physical layout of the connectors for the Diesel starts at page 8W-91-31. :wink:

Nope, the 3.4 is only there with ignition on. I haven't tested the voltage at the starter under load yet, but I will. All wires and grounds ohmed out very good, but that doesn't mean that they can allow for proper current flow.

Mountainman · **Posted:** Fri Dec 13, 2019 5:00 pm

Starting a new thread. A leaky injector saved the bearings!

WWDiesel · **Posted:** Fri Dec 13, 2019 5:12 pm

Mountainman wrote:

Starting a new thread. A leaky injector saved the bearings!

Must be connected to start connections?

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