1997 Lariat won't start after heater core.
 

Hey guys,

Just replaced both the blend door and heater core in a family friends '97 F150 Lariat w/ a 4.6L.

Got everything back together, and now the truck won't start. When I turn the key, I don't get any clicks, no cranking, nothing.

The power windows, locks and radio all work.

I have two wire harnesses that I am unable to figure out where they go, they are:

3U2Z-14S411-XTA
According to the connector catalog, this controls:
Electric Brake(towing)
Mirrors
Trailer Lamp
Seat track adjustment

The other connector is:
3U2Z-14S411-LA
It controls the mirror sideview

Neither of these connectors seem like they should cause an issue if not hooked up.

On a final note, yesterday, there was a light on the dash that said THEFT that as on. Today, it is not.

Also, the shifter seems a bit loose, not sure what to make of that.

Any help/tips would be much appreciated.

Thanks,

Gfx

The THEFT light is the PATS system. It should be blinking with the key off about every 20 or 30 seconds. When you turn the key on if it blinks fast then you are using the wrong key or you have tripped the anti theft system. However it should still crank but not start.

From what you posted I would suspect the park lock out isn't right. The loose shifter means the PCM thinks the truck is in gear and won't engage the starter.

Try putting it in neutral and see if that helps.

There is supposed to be a screw or bolt at the bottom of the steering colom, take a look and check that everything is tight down there.

Good luck. I'm sure some smarter guys will chime in soon.

i dont think the 97 and 98's have PATS. Well, mine doesn't.

The OP posted that he had a THEFT light on the dash. But I don't know fer shur-fer shur, figgerd if he had the theft light that it has a PATS.

Maybe a trim level thing or an option, just guessin.:think:

i can tell there is a theft symbol when the sun hits it right, but i dont have a chipped key, and it still starts up... back to his issue. Did you remove any wires while doing this, or worse unhook wires and forgot where they went...

I've read that PATS didn't start for another couple of years, but I'm a Ranger guy,(own 4) not an Fullsize guy, so I can't promise.

I've been wondering about how the thumb screw that seems to set where the shifter lands on the dash.

Did I remove any wires? Yeah, a lot.

Does not have a chipped key, but does have a remote that doesn't work.

Did you try starting it in neutral?

There is no PATS system in a 97 or a 98. The minimal factory anti-theft system is a perimeter defense system. it just flashes the THEFT light and, if triggered, blows the horn and flashes the parking lamps. It does not interfere with engine starting or operation but it is operated by the module that also controls remote keyless entry.

The loose shift lever is pretty common. Usually, it's either loos Torx-head screws on the column or worn shift tube bushings.

Do NOT mess with the pointer adjustment!

Do try starting it in Neutral. If the shift lever is badly out of alignment due to looseness, you may find the starter motor circuit interlock circuit completes when the shifter is in a position adjacent to neutral.

Otherwise, we need a more complete set of observations as to what powers up and what doesn't. Also, any observations about what does and doesn't happen when the key is turned to START.

The connector part numbers from the connector catalog are example usages, not a full list of them. If you did a stare and compare to the connector, it might be used for that in additional to other items.

The 97/98 had a perimeter alarm that had a starter interrupt circuit in it, if equiped. This is the theft light in the cluster for the 97/98 MY trucks.
There was a version of the RAP for the 97/98 ( not the same RAP used in the 99 & 00 MY ) that operates a starter interrupt relay in the RPO relay block. This is a normally closed relay that routes the power from fuse # 21 ( hot in start position ) through the DTR and to the starter motor relay on the firewall as the Tan w/ Red wire.

Could be a connector for the RAP is unplugged or the ign cylinder tamper switch ?

Starting in Neutral is a good test point, as is check for + VDC at the Tan w/ Red wire while starting the truck ( need 2 people or some long leads so you can see the meter ). This wire should have + VDC when the key is in the start position. If not, next place to check is the Dark blue w/ Orange stripe wire going to the DTR.
- This is assuming that you checked fuse #21 ( junction box panel ), with a meter on both sides to a known good ground. If this is not functioning no amount of checking is going to start.

Sorry, I took so long to get back, just getting in from work.

Will not start in neutral. It does the exact same thing.

Unfortunately, I already messed w/ the pointer adjustment.

The shifter just doesn't seem to lock in anything but park. Makes me think it's a possible linkage issue? I've never owned an automatic, so the mechanics of this are kinda lost on me. But, I guess now's the time to learn.

Here in a bit, I'll check the voltages and get a detail of what is and isn't working.

Thanks guys,

Gfx

Alright, Results for fuse 22.

Left side is reading open to ground.

Right side is reading as follows in these scenarios:

Key out of the ignition - 60 Ohms
Key in, auxiliary position - 0 Ohms
Key in, start position - 39 Ohms
Key in, after being returned to the off position, 39 Ohms for about twenty seconds, then a relay clicks and it goes back to 60 Ohms.

Not sure where the Tan w/ red wire.

Found the Blue w/ orange wire (as long as it's the only one). No voltage w/ the key in start position.

Check list of working, and nonworking.

Radio - works
Drivers side window - works
Passenger side window - works
Dome light - works
Other Cabin light - works
Power locks - works
Passenger mirror x axis - works
Drivers side mirror y axis - works
Lighter - works
Blend door actuator - works
All seat adjustments - works

Passenger mirror y axix - Does not work
Driver side mirror x axis - Does not work
Blower motor - Does not work
A note on the blower motor. If you set it to high, "Check Susp" lights up on the dash.

Let me know what else you guys may need.

Thanks again.

sorry I should have been more clear.

You are checking VDC from ground to either side of the pin on the back of the fuse.

The starter motor relay is on the firewall under the hood of the truck. Should be 3 wires to it. 2 are battery size wires ( ~ 4 AWG ) , the other ( Tan w/ red ) is a 16 AWG wire.

The Dark blue w/ Orange stripe wire is at the DTR on the side of the transmission, is this where you found that one ?

Ahh, that makes more sense.

Well, judging by the resistance readings, when the key is in the start position, it will be shorting everything to ground. If the fuse is in, that is. Therefore, as long as the fuse is not blown(it's not) then there should be the same voltage on both pins.

Will check those two wires when I get off of work tomorrow. Unfortunately, I didn't check the correct wire. Missed the fact that you said its at the DTR.

sscully,

Yep, you're correct about the starter interrupt relay in certain ones with the RAP module. I remembered my old 97 had the more rudimentary system without that feature.

Check to see if the shifter cable is broke under the dash, had this happen when I did a core in a friends truck. The cable can bind and break if the cable is still hooked up to the lever on the column,when you drop the column down to drop the dash. The casing on the cable will break, and the cable inside the casing will bind and not go in park. Hope this helps. Good luck.