Monthly Archives: June 2015

K2500 injectors and O2 sensor

I ordered two fuel injectors for the K2500. Maybe tonight I’ll install them along with the new O2 sensor and see if that makes any difference.

The code 42 I keep getting indicates a problem with the timing, either with the ignition control module itself or with the wire between it and the computer. I should verify that the timing wire is in fact connected and not broken somewhere.

K2500 coolant sensor, injector news

At the suggestion of someone on the Chevy forums, I replaced the K2500’s coolant temperature sensor. There are actually two: one in the intake manifold (the one I replaced) which feeds data to the computer, and one in the driver’s side head (which does nothing more than run the temperature gauge on the dashboard).

It made no difference, unfortunately. The engine runs the same and the SES light is still on.

While I was working on that, I took the air filter housing off and looked at the injectors’ spray patterns with a bright light and while the engine was running. Instead of a fine mist, the injectors are dribbling fuel down the bores. I could actually see individual drops of gas running down the throttle body walls. So no wonder why the engine’s running so rich. It’s time to replace the injectors.

I charged the air conditioner, too. Unfortunately, that made no difference; the compressor clutch seems to be disconnected, and I can’t find where the connector is. Without it, the AC’s not going to do anything. And to top it off, once I shut down the engine I could hear the refrigerant leaking back out of the system somewhere near the consensor. So I’ll need to fix that before I try to recharge it again.

Also, I suppose I should pull a vacuum before I try to charge it again. Who knows what moisture there is in there.

I successfully added refrigerant to the Ram, too. Formerly the compressor was cycling on and off and it wasn’t blowing as cool as I wanted. Now it’s staying on constantly and the low side pressure was staying at about 40 PSI. High side was approaching 350 PSI, but it was also a hundred degrees outside when I was working on it.

I ordered two fuel injectors from Rock Auto, which include hardware (presumably, O-rings and gaskets).

Parts, finally

The funds for car parts were authorized after a long drought. So I ordered parts.


Right front window regulator (various mfr, Rock Auto pn MB1351102) $32.79

New radiator (Nissen 1405002303) $207.95 from BuyAutoParts via Amazon (excellent, since the cheapest I could find it elsewhere was $275)

Upper radiator hose (APA W0133-1715721-APA) $28.39 from Amazon

Serpentine belt (Contitech 6K X 2145) $23.25 from Pelican Parts

Expansion tank cap (Rein OEM) $6.25 from Pelican Parts

Windshield wiper insert (left) (Bosch 25″) $14.25 from Pelican Parts

Windshield wiper insert (right) (Bosch 28″) $14 from Pelican Parts

Fuel filter, spin-on (Mahle) $9 from Pelican Parts

Fuel pre-filter, in-line (Bosch) $2.75 from Pelican Parts

Transmission filter kit (Elring Klinger) $13.75 from Pelican Parts

Oil filter kit (Hengst) $9.25 from Pelican Parts


Temperature sender (Airtex 1H8) $5.34 from Rock Auto

Distributor cap (Airtex 1A7) $4.14 from Rock Auto

Distributor rotor (Airtex 1A8) $1.06 from Rock Auto

Spark plug wire set (Standard Motor Products 26889) $13.02 from Rock Auto

Serpentine belt (Dayco 5060955DR), $11.39 from Amazon

Transmission filter kit (Pioneer 745031) $12.60 from Amazon

Oxygen sensor (Denso 234-1001) $13.51 from Amazon


Serpentine belt (Gates K081264) $30.57 from Amazon

Ram codes

I took the IPM (integrated power module, aka the fuse box) apart, cleaned all its connections, re-electrical taped everything, and put it all back together. No change in weird electrical behavior.

But I was able to pull codes using Torque. I got:


Torque lists this as: Powertrain – powertrain induced chassis pitch output circuit

but the Chrysler-specific description for this code is “J1850 Communication Bus.”



Torque lists this as: Powertrain ( 1) ECM/PCM power input signal intermittent

This is an industry-wide description and the manufacturer doesn’t matter.

So the ECM confirms that there’s a problem with the bus communication. I’m guessing that’s the symptom, rather than the cause — the cause is that the ECM or PCM isn’t getting reliable power.

Here’s some info about P2509:


Continuous – Key on or Key off.

Loss of voltage detected at the ECM for a calibrated amount of time.


* Poor connections at the batteries
* Low battery voltage
* Open fused B+ To ECM
* Open ground circuit
* Battery + shorted to other circuits
* Return circuit shorted
* Battery + shorted to ground
* Intermittent condition


And this is certainly interesting:

more p2509

Case Number K24612402
Vehicle Issue MIL. P2509. The engine may stumble or stall out.;12 volt power (unswitched) and the ground circuits to the ECM are good. Batteries and charging system operation are good. If applicable (2006 and 2007 MY trucks), the ECM has already been updated per TSB 18-001-07.
System or Component Die out / Stall,Hesitation / Sag / Stumble;DTC / Error Message;ECM
Recommendation If the problem can be duplicated, disconnect the fan clutch 6-way connector and check if the concern still occurs. If the problem no longer occurs, replace the fan clutch assembly.


And …
Case Number K13878564
Vehicle Issue Engine Stalls Out. ‘NO BUS’ Message Is Displayed. P1652.;Power and ground connections to the Cummins ECM are good. P1652 and P2509 are set.
System or Component Die out / Stall;DTC / Error Message;Electronic Control Module,ECM;Yes – Intermittent,Yes – Continuously
Recommendation Inspect the wiring harness near the C108 (14 pin) connector. This connector should be at the back of the engine, near the transmission bell housing.


The combination of both P1652 and P2509, and the fact that they’re both correlated with that wiring harness near the transmission bellhousing, makes me think I really need to have a look at that. I also need to take a closer look at the radio harness to make sure it’s not grounding out at all.

More thoughts on K2500 fuel economy

The thinking is that contributing factors to the K2500’s bad (though getting better) fuel economy could be worn-out injectors (about $50 each from Rock Auto, or $70 from AutoZone). It could also be a bad O2 sensor. Since I’ve replaced the fuel pump, throttle position sensor, MAP sensor, and ignition module, these are the remaining likelies. I suppose, also, I could stand to replace the spark plugs, wires, rotor, and distributor cap, though honestly I’ve never seen performance improve as a result of replacing these so-called tune-up items.

Ram radio not the cause

This thread gave me hope that maybe my electrical problems had something to do with the radio. While the problems did happen long before I replaced the radio, I hoped that maybe it was something wrong with the original radio and continued with the new one, or something.

Unfortunately, after unhooking the radio completely, the symptoms are unchanged.

Trailer plug and electrical craziness

I finished hooking up the new trailer plug (combination 7-pin and 4-pin), along with the plug in the bed too. I bought a little butane torch and for the first time ever, managed to do a fairly good job of soldering wires (sometimes as many as five) together.

I wish I could test the work, but the electrical issues in the Ram have just gotten worse. The dashboard is going crazy and now has started displaying “no bus” with the key on/engine off. I need to check several more things, such as: the radio connections; corrosion under the fuse box; and the ground strap at the bellhousing. Cleaning the connectors on the back of the instrument cluster had no effect, nor did cleaning up all the battery posts, all the ground connectors in the engine compartment, and the main fuse box power lead.

Ram exhaust brake

In an attempt to figure out just what’s causing the gauges to go nuts, I looked into how the exhaust brake is hooked up. That’s because according to PacBrake’s documentation, the exhaust brake is supposed to be hooked up through the ECM.

Well, this one isn’t. This one wasn’t set up at all according to PacBrake’s instructions. There’s no air tank, no relays … it’s a very simple, direct connection from the compressor to the exhaust brake, and the compressor power is switched by the switch under the dash. That’s it.

How it’s supposed to be is, the compressor should be hot all the time, keeping the (missing) air tank pressurized, via a pressure switch. There’s supposed to be a switch on the gear shift that activates the exhaust brake solenoid. Both the pressure switch and the solenoid should be wired up through two relays.

Hooking it up the way it’s supposed to be lets you leave the exhaust brake on all the time (though you can turn it off with the shifter switch), and it will automatically turn off once the engine hits 900 RPM and back on when it drops below. As it is right now, I have to remember to turn it on when I’m decelerating down a ramp, and then back off again — otherwise the EGTs go through the roof. Also, I imagine the compressor has to stay on constantly, rather than cycling as it would with a pressure tank.

Well, the good news is this can’t possibly be affecting how the ECM works, so this is one fewer cause of the problem.