99.5 7.3 Won't Start

[PLS13601]

I need some quick advice where to start. Have not driven the truck in a week, ran fine for months. New batteries last fall, gave a quick charge, now showing 13.3 volts, while trying to start, volts drop to 12.0. Replaced CPS, due to no tach movement, did not fix it. Engine will not turn over at all. I have random rapid clicking on the vehicle security system box under the steering wheel. If I double click the fob, it goes away.

Any input of what to check would be appreciated!

[klhansen]

Relay clicking is a sign of weak batteries.
Your voltages kind of say that's not your problem, but you might double check with a load test and also check the battery cable connections. If that apparent good voltage isn't getting past the battery clamps it won't do any good. Also check the cables for signs of internal corrosion. If the conductors are turning into green mush, they won't transmit any power.

[PLS13601]

Thanks for the input. I gave a quick glance at the cables, no visible signs of corrosion, I will check further in the morning.

A little more backgroud, this truck was stolen in January of this year. Recovered after two days with little damage other than the trashing of the ignition and steering column. I do recall the repair shop saying that the batteries took longer than normal to come back up to charge. I have been driving it at least twice a week (sometimes more) since then. I did a 500 mile road trip towing our camper over the fourth of July. I used it more in August around town than anytime since the theft. I do live in Las Vegas and the heat is a killer on batteries here. 2-3 years max before replacing is the general rule. I guess what puzzles me is there is NO cranking whatsoever. Again, I will investigate the cables in the morning and post my findings. Can you recoomend batteries? I have been told by several people lately that Optima yellow tops are the way to go here in the desert. Currently I have Interstate.

Again, thank you for the help!

[JimTJr]

Well, have you crawled under and tried shorting the contacts on the starter with the key on? Maybe your solenoid is bad?

[PLS13601]

Battery cables are good. Load test still good. I checked my neighbors truck (99 F350 w\ diesel) and my volt load matched his pretty close, even when trying to crank. Truck still will not start or crank w\ key. However, jumping across solenoid contacts fires it rightup! Could it be the "Ford vehicle security system box"?

[Mad Max]

Looks like the damage that was done when the truck was stolen was not fixed correctly. I bet your problem is with the ignition switch.

[ddm502001]

I would fall back to the security box or the control leads from it to the starter remote solenoid and/or the solenoid as well. Could be the theives overheated something in their process.

[klhansen]

As far as I know, power from the battery thru the ignition switch to the starter solenoid doesn't go thru the "security box". My wiring diagrams show the following path for the start circuit:
From Fuse #20 (50A) under hood To Ignition Switch contacts B4 and B5
From Ignition Switch contact "ST" to Fuse 20 (15A) under dash
To Clutch Pedal Position Switch (or CPPS jumper on automatics)
To Digital Transmission Range Sensor (on Automatics only)
To the starter motor relay mounted on the fender.
This is to get power at the small terminal on the starter relay.

Jumpering across the two large terminals on the starter relay wouldn't necessarily mean the relay is bad, but jumpering 12V to the small terminal and getting it to crank means it's good. If you jumpered to the small terminal and made it crank, start backing up the circuit described above.

I agree that if you had repairs to the ignition cylinder and steering column, that would be a likely candidate for the source of the problems. The ignition switch itself is mounted under the instrument panel and activated by a pushrod from the cylinder. If things aren't right there, the switch may not be fully engaging in the starter circuit. There are actually 4 separate switched circuits in the switch body.

Hope that helps.

[Mad Max]

Nice info Kl, I think I will print it and put it in my truck just in case....

[mbachand]

I have a similar no crank problem with my 99 7.3. I think it is related to the factory security starter kill option. The problem is intermittent and usually goes away when I lock and unlock the security system. Does anyone know where the factory security starter kill relay is located?

[mbachand]

Here is an update. My no crank problem stayed long enough to diagnose today. It was the Ford security system, specifically the starter kill relay inside the security module. The relay interrupts the circuit from the ign switch to the starter solonoid. The relay was staying open even when the system was disarmed. I removed the 2 pin starter kill connector from the system (clearly marked on the back) and put a jumper across the plug. Starts fine now. I also had a look inside the system since it easily opens up. There are 4 dip switches inside. They must be for setting different features, but there is no description. Does anyone know the function of the switches. The manual talks about some dealer setable features which these must be for.