Winback

Truck was being diagnosed after discovering no ground from PCM to pin 85 of the ac clutch relay in the engine bay fuse box after somebody other than me worked on the truck. Truck started fine, fuse box was jumped to provide ac, all sensors are good and AC worked. Jumper was left in all night, battery dead. Replaced battery, was old. After a few days jumper was forgotten again, dead battery, had it properly charged and tested at O'Riley where it was bought, good. Replaced jumper with the relay.
Now it doesn't start. But what's interesting is yesterday I got it to start twice while physically pushing on the passenger side fuse panel, specifically the relays first, then while wiggling fuse 32 with pliers. Can't recreate.

Order of events of new problem:
Key turn on, dash on, radio screen on, climate control module lights on, door/window switch lights on. (Blower motor works, it's a great way to test the other relays too.)(Headlights turn on)
Key start, relays click, radio screen turns off, door/widow switch lights turn off, dash stays on, blower motor stays on, headlights stay on, nothing from starter, not a sound. Release key from start, relays click, radio screen and door/window switches come back on.

Starter is brand new, doesn't mean that isn't the issue though, gonna look how to test it properly, suggestions are welcome as I'm by myself, so record meter with phone and alligator clamps on probes. I'm getting 11.98v to pin 86 on starter relay, checked relay in blower motor circuit and works. Now I understand the PCM provides ground to pin 85(it's getting ground at key on from PCM), constant power to pin 30(11.91v), ground for S terminal on starter is 87/87a.(has ground)

There is 12.4v to the starter power lug, shows 12.4v from power lug to solenoid lug and power lug to S terminal. Last night I tried jumping it with pliers, odd angle for screwdriver. Had nothing from starter. No gear turn or shaft extension. Few sparks on solenoid, good sparks on S terminal. Should I just bite it and remove starter for testing? Or did I do something wrong?

ProjectSHO89

That's supposed to be HOT IN START, not ground. It's supposed to energize the starter solenoid when starting.

One at a time, connect your meter between ground and the main battery feed at the starter and then the small "S" terminal. The S terminal should go to battery voltage if everything "upstream" is working. The main power feed should remain at or near battery voltage when the solenoid tries to engage the unit. Since the starter didn't engage when you shorted those two terminals together, you're left with either a bad starter or a bad cable/connection back to the battery.

Report readings.

BTW, I developed the habit of having starters and alternators tested in the store before I pay for them. I've caught a couple of duds before getting them back to the shop and discovering the hard way that they were bad out of the box.

Winback

T'was a bad starter. Took it off, battery cables to energize. Nothing, not a hum. Was only installed for 2 weeks, sat around for a while, still had 13 days of warranty, haha.
New one in, start first crank. At least everything else is working. Caught a few bad fuses along the way and found a parasitic draw from an old shorted led light bar wire harness on the bumper.

Now I'm back to where I was supposed to start, ac clutch relay not getting ground from PCM. Guess test the pin 85 wire for a break between it and PCM?

BareBonesXL

Might be that the PCM supplies the ground when certain conditions are met. Sensor readings and switch settings and stuff. That is generally how the PCM works. It's not meant to be an always-grounded ground.

Winback

I tested all the other switches, I read that the PCM needs signal from high pressure sensor and low pressure sensor and possibly the evaporator temperature sensor. Works perfectly with the relay jumped, pressures are correct. So my only thought is bad wire, or bad evaporator temperature sensor.....

I'm currently trying to find the wiring diagram or its location in any repair video but I have been unsuccessful to see if I can test it without removing the dash and likely opening air box. The videos are all about the heater core or evap coil and never mention the sensor. Any info would be helpful. If I can find the wires running out of the box I can nick the two wires and jump it, if clutch engages with relay then that's my culprit.

Trying to find a wiring diagram, trying.

BareBonesXL

This video is worth watching I think. The usual guy.

ProjectSHO89

The 2005 does not use an evaporator temperature sensor, it uses a low and high pressure switch in series to tell the PCM when to cycle the compressor clutch.

Winback

That's what I was hoping. What a relief. Okay so I found the Hanes pdf on a forum, page 35. Looking at the middle PCM cable snake, disconnected, the top row bottom right Pin 18 should have 10+v at 'ignition on'. I'm only getting 3.2v.
Pin 19 I'm getting 12+v.

Also noticed that if I unplug the low pressure switch while truck is running it stalls the truck out. Normal? Still haven't looked at a wiring diagram. This is with the relay in, not jumped.


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Edit: I noticed the AC dash button stays lit no matter what setting, and the cabin air button is struck with the top not releasing and can't switch on/off. I also discovered a loose wire splice, White w/purple stripe. Wiggling causes cabin air light to turn off and on as well as air box switching accordingly.

ProjectSHO89

Is this a manual or automatic climate control system?

Winback

Manual climate control.