Manager Forum

Engine dies when you honk the horn and when A/C cycles. Always restarts. Codes P0603, P0344, P0677. Cam sensor was replaced recently. Intermittent glow plug code. KAM error. Battery was low.

If battery is low, it has to be real low, any extra drain on it can and usually does cause it to die. Fully charge both batteries and check charging system. It may take a few seconds at a higher rpm for the alt to kick in. If one battery is weak we always replace them in pairs making sure the amp is correct. A low battery will cause multiple codes.

Oh yes, and don't forget those famous fusible links that are hidden in the wiring harness. I see in a wiring diagram that the same fusible link that feeds the AC system also powers the PCM and IDM. I agree with steve about the batteries but I have also seen a fusible link that is mostly blown do some strange things.

You mean where a loose battery wears through the links where they pop out of the harness?

steven kiser wrote:You mean where a loose battery wears through the links where they pop out of the harness?

Not sure I understand what you are referring to steve.

I've had a few Fords where the battery not being secure and shifting around on the housing has worn through the wiring harness that wraps around the inner fender next to the battery compartment. I lost count of how many dsl trucks that have come in here with hard starting issues and both batteries are AAA, Auto Zone, or installed at some other shop where they used something close and the batteries are just rattling around. I've had them wear holes in the side or bottom and leak acid onto harness connectors and such. I'm tracking how many jobs i get because of improper prior repairs and it around 8% right now.

Yea well. All those competent guys out there making some big bucks doing work like you just described. Yes, I have seen stuff like that as well and it really irritates me. I mean, anybody can make a mistake but some of this stuff is beyond that. Like what you are describing. It does seem to be perhaps more common on the diesel powered trucks. We see alot of the acid seepage due to loose batteries and all the problems that creates.

Ahhhh, the electrical issues on these diesel powered Fords! They are good for business.

Checked all grounds, power connections, fusible links, central fuse box, reference voltage to cam sensor, crank sensor, ICP sensor. OK. No lose of voltage to sensors when A/c or horn cycles. Replaced fusible link between battery and alterntor. Was ok for a day. Alternator has bad diodes. Alternator only charging at 2/3 capacity. Will replace with customer approval.

Still acting up. Cuts out when A/C cycles, honk horn. GEM failure? HELP

Are you saying that the engine shuts off when the AC cycles or the horn is blown?

Sounds like the issue may be in the power distribution box under the hood. The horn and compressor relays are there. Un snap it and look at the wiring on the underside. There may be a melted or chafed wire in the spagetti.

YES. Engine dies only when A/C cycles "off" and when horn honks. When horn is grounded to honk. Engine dies.

FIXED. Someone had changed wiring harness to A/C compressor. Power wire from heater control feed directly to compressor clutch. Signal wire to pcm was tied directly to this wire. This caused pcm to shut down when A/C clutch cycled.

Ahhhhhhh. The feeling of curing a sick vehicle! Ya gotta love it.

By the way, how did you discover the wiring issue to the AC compressor?

I got a wiring schemtic from ford and wire it up like the schematic.