No start condition

[Casey_SS]

Anyone got a list of the connections required for the starter to engage on 4th gen? I know there's a switch on the clutch pedal and the VATS deal but I think there's more than just those two.

Got everything wired up, all connections show good on the ohm meter and I have 12.5 volts on the starter, alternator, fuse panel, and junction box for the fusible links. there's just something preventing the starter ground from engaging when I turn the key. The gas tank is still out of the car....does it need a signal from the fuel pump?

I found you can easily swap the connectors for the brake pedal and the clutch pedal - switched these with no change. VATS is still enabled but will be tuned out hopefully tomorrow once I get a new license key for my tuning software (long story). What else?

[Fbody383]

http://shbox.com/1/starter_charging_96.jpg

Casey, this is one of those sites you just need to know about. This is for a '96; he also has a '93 and '95. Yours is likely similar.

Is the BCM still in the car? Looks like you need the BCM to take the theft deterant relay to ground to let the clutch safety switch energize the starter.

[Casey_SS]

Yeah, that's a great site but I had forgotten about it. this is exactly what I needed. Thanks!

Yep, BCM is still in the car and connected. Looks like VATS is the most likely suspect with all the other circuits testing good. Will tune that out tomorrow and see what I get...

Thanks!

[GlennCMC70]

Is the cluster plugged in?

[Casey_SS]

No....would that cause the starter to not engage?

[GlennCMC70]

I've seen LS 4th gens not start due to blown inst cluster fuses.

Try it.

[Casey_SS]

No dice. I've got all the normal dash lights, volt gauge works, etc. but starter still no turny. Double checked the fuses and they're all good...VATS?

[GlennCMC70]

There is that small pair of wires on the colum w/ the orange sleeve on it. That is the VATS circuit from the key. Is it plugged in?

[cobra132]

On the fords there is a feedback from the fuel system.

[AllZWay]

Double the check the wiring to the bottom of the steering column. I had a loose connection in the connector to the steering column.

Check and recheck the whole vats circuit.... that system is a real pain. I bought the vats bypass to avoid that crap after I had trouble.

[Fbody383]

Check and recheck the whole vats circuit.... that system is a real pain. I bought the vats bypass to avoid that crap after I had trouble. I thought the VATS was in the anti-theft system and in the factory wiring migh shut off fuel pump and definitely shut down injector firing but NOT in the start circuit.

Motor not continuing to run I would lean towards VATS, but no starter turn over makes me think anti-theft relay.

Find the starter relay in the interior wiring. Of the top of my head I think the heavy purple wire goes to the starter solenoid. Check voltages at that relay socket.

[NickV]

The gas tank is still out of the car....does it need a signal from the fuel pump?


When we put the Painless harness in my car, there was a signal wire that we hooked up to a +12v source to trick it in to thinking the fuel pump was on (because I have my fuel pump on a separate switch), or else it wouldn't start.

When we had VATS issues, the motor would at least try to turn over, but never start.

[Casey_SS]

And the saga continues.....tried pulling the tune off the PCM to edit VATS out and it can't get a response from the PCM. Looking through schematics to figure out which wire supplies PCM power to test to see if it's getting power....

Just tested all the harness grounds I'm aware of and they all show 0 - .2 ohms to the battery ground. I tested the one near the steering column, two near the driver seat, and one near the glove box. Are there others?

Only things not connected are what went to the door harnesses and headlight switch / dimmer.

I know the harness is getting power because I have idiot lights and I know the BCM is working because my daytime running lights come on when I turn the key on (light sensor is buried in a dark place).

What am I missing?

[GlennCMC70]

OBDII port gets power from the lighter or seat circuit. Check for 12V at the OBDII port.

Also look at the connections James mentioned at the column.
You also need to check the start relay. Check to see if your getting the command for the relay to close (small wires - one is ground and one is power to the relay) and that 12v is coming into the relay (purple wire) and out of it if it is closing. I remember there being a weatherpack for just that purple wire under the hood behind the PCM.

So, check that the start relay is clicking, if not, find out why. If it is, the computer is not the issue, but power to or from the relay is. You must start here so we/you can tell where to start next. This will isolate the problem to computer/signal or relay/power.

A test light is good for this type of troubleshooting. Make one from a 12v bulb if you dont have one. I use an old license plate lamp w/ long leads on it w/ aligator clips on the end. place it in line of sight to see if you get a go/no go indication.

[Casey_SS]

OBDII port has 12.4 volts. PCM has 12.3 volts. I don't have a single purple wire coming out behind the PCM but I do have a rather large (10-12ga?) purple wire in one of the harnesses coming out in that area. It goes down towards the starter so I'm assuming that's the one. If so, it does not appear to be getting power when I turn the switch to "start".

Not sure where to go next except pull the dash back off and go digging around the column and hope I find something. Gonna eat first, drink a beer, and hide all the dammit tools before proceeding further.

[Casey_SS]

One more thought - back to basics. The only things I changed on the car are as follows:
Battery moved to trunk
2ga wire from + battery to master disconnect
2ga wire from - battery to rear frame rail
2ga wire from disconnect to bulkhead to stock + battery cable going to starter
Stock - battery cable goes to stock ground point near junction box (grounds engine to body)
Alternator & junction box wires originally on stock + battery cable go to bulkhead
16ga wire interrupts + wire on ign. coil via disconnect
Removed door / cross body section of harness
Pulled HVAC, Airbag, wiper/wash, radio accy , courtesy, defog, windows, & radio fuses

That's all that changed from "known good"....anything suspicious here?

BTW - Glenn - there's a relay under the dash with a big purple wire going to it that DOES click when I turn the key to start. Not sure why it's not showing power downstream...no visible problems in the path.

[mitchntx]

OK REAL basic ...

There is a small wire attached to the starter solenoid, right?

[Casey_SS]

Yes. I didn't touch any of the wiring under the car, just removed and reconnected the interior harness minus the door / cross body section.

[mitchntx]

You have 12V at the starter? How about at the solenoid when the key is turned to start?

Nick is correct ... VATS would prevent it from starting, not engaging the starter.

If the relay is clicking, run a jumper wire from the relay output straight to the starter.

If it engages the starter, it's gotta be in the wiring loom.

[GlennCMC70]

One more thought - back to basics. The only things I changed on the car are as follows:
Battery moved to trunk
2ga wire from + battery to master disconnect
2ga wire from - battery to rear frame rail
2ga wire from disconnect to bulkhead to stock + battery cable going to starter
Stock - battery cable goes to stock ground point near junction box (grounds engine to body)
Alternator & junction box wires originally on stock + battery cable go to bulkhead
16ga wire interrupts + wire on ign. coil via disconnect
Removed door / cross body section of harness
Pulled HVAC, Airbag, wiper/wash, radio accy , courtesy, defog, windows, & radio fuses

That's all that changed from "known good"....anything suspicious here?

BTW - Glenn - there's a relay under the dash with a big purple wire going to it that DOES click when I turn the key to start. Not sure why it's not showing power downstream...no visible problems in the path.

OK, no power downstream (out of the relay). How about power into the relay (upstream)? Not power that makes the relay close, but power that the relay is switching open/closed.

[mitchntx]

You have 12V at the starter? How about at the solenoid when the key is turned to start?

Nick is correct ... VATS would prevent it from starting, not engaging the starter.

If the relay is clicking, run a jumper wire from the relay output straight to the starter.

If it engages the starter, it's gotta be in the wiring loom.





One more thought - back to basics. The only things I changed on the car are as follows:
Battery moved to trunk
2ga wire from + battery to master disconnect
2ga wire from - battery to rear frame rail
2ga wire from disconnect to bulkhead to stock + battery cable going to starter
Stock - battery cable goes to stock ground point near junction box (grounds engine to body)
Alternator & junction box wires originally on stock + battery cable go to bulkhead
16ga wire interrupts + wire on ign. coil via disconnect
Removed door / cross body section of harness
Pulled HVAC, Airbag, wiper/wash, radio accy , courtesy, defog, windows, & radio fuses

That's all that changed from "known good"....anything suspicious here?

BTW - Glenn - there's a relay under the dash with a big purple wire going to it that DOES click when I turn the key to start. Not sure why it's not showing power downstream...no visible problems in the path.

OK, no power downstream (out of the relay). How about power into the relay (upstream)? Not power that makes the relay close, but power that the relay is switching open/closed.

Do you have my posts blocked or do you just like seeing your name in print?

[David Love AI27]

You have 12V at the starter? How about at the solenoid when the key is turned to start?

Nick is correct ... VATS would prevent it from starting, not engaging the starter.

If the relay is clicking, run a jumper wire from the relay output straight to the starter.

If it engages the starter, it's gotta be in the wiring loom.





One more thought - back to basics. The only things I changed on the car are as follows:
Battery moved to trunk
2ga wire from + battery to master disconnect
2ga wire from - battery to rear frame rail
2ga wire from disconnect to bulkhead to stock + battery cable going to starter
Stock - battery cable goes to stock ground point near junction box (grounds engine to body)
Alternator & junction box wires originally on stock + battery cable go to bulkhead
16ga wire interrupts + wire on ign. coil via disconnect
Removed door / cross body section of harness
Pulled HVAC, Airbag, wiper/wash, radio accy , courtesy, defog, windows, & radio fuses

That's all that changed from "known good"....anything suspicious here?

BTW - Glenn - there's a relay under the dash with a big purple wire going to it that DOES click when I turn the key to start. Not sure why it's not showing power downstream...no visible problems in the path.

OK, no power downstream (out of the relay). How about power into the relay (upstream)? Not power that makes the relay close, but power that the relay is switching open/closed.

Do you have my posts blocked or do you just like seeing your name in print?

He just wants to be like you.... bet he already has a cat...

[Casey_SS]

All right, this is kicking my ass. I can jumper across the starter terminals and it cranks like a mofo. I have no power going to a relay with a purple wire on it that clicked last night with key turned to start but doesn't click tonight. The DRL module (daytime running lights) clicks every 5 seconds with the key on...? I also have no power to / from the clutch switch in any key position. Time to test further back...

There's a red wire going to the ignition switch coming from the junction block fed by the battery. This wire has 11.8 volts at all times and is marked 12v constant on the wiring diagram. There's also a yellow wire marked starter which has no power in any key position. Not sure what to make of that but I know I have power to the switch.

Coming out of the switch, there's a purple wire that shows 11.7 volts with key on but drops to 0 in start position. It goes into a big connector and then into the main harness going to passenger side. It shows the same behavior at all points tested. Also tested every single wire coming out of the switch - only one shows power in the start position but it's brown and is also hot with the key just on. This purple wire is the only one that changes and it goes to 0. Bad switch?

Still a bunch of other stuff to do and I have 3 business trips this month....running way short on time. I think I'll just wire up a push button directly to the starter and bypass the switch altogether. Still doesn't address the PCM not responding, which has power at the appropriate pins (31 & 15 on the black connector for anyone who may need it later)....I'm more worried about this than the starter problem to be honest. All the grounds I can find test good though so not sure what else to check / do on this one. I'll get the tank back in tomorrow night, bypass the switch and hope it runs. Thoughts?

[GlennCMC70]

Sounds like the brown wire is the 12v supply to the purple thrru the relay. I seem to remember thaving those colors on the start relay.

Remember, when you start the car, some stuff turns off allowing full power to the starter.

If the relay doesnt click, you have a differnt problem.

[AllZWay]

Still sounds to me like the Vats is limiting power to the starter relay.

[Fbody383]

This purple wire is the only one that changes and it goes to 0. Bad switch?

Looking at the 95 and 96 ignition switch diagrams from shbox:

RED ~ +12 from batt
BRN ~ +12 active ACC to RUN, through BCM (probably includes retained accessory power)
PNK ~ +12 switched RUN and START, PCM/Gauges/Injector fuse power
ORG ~ +12 switched RUN (prob START), Ignition coil
YEL ~ +12 switched START, powers theft deterrant relay/power to clutch switch

Begin again at the ignition switch, the BRN may go flat in START.

The YEL should only be hot in start and is the supply to the clutch switch and relay.

I also wonder if you need to ground the coil of the theft deterrent relay (YEL/BLK).

Too bad you're not closer; it's probably something simple. Well, it's easy from here.

[Casey_SS]

Ok....after one hell of a fight, the gas tank is back in. Not surprisingly, it still doesn't start using the key. It does fire right up jumping the starter terminals though and seems to run fine, which is what I was hoping for. I'll wire up a simple switch directly to the starter, finish the rest of what I need to get done to make ECR, and come back to the switch troubleshooting as time permits.

Many thanks to everyone for all the advice and reference data...I really appreciate it.

[Fbody383]

It does fire right up jumping the starter terminals though and seems to run fine, which is what I was hoping for. Awesome! If it will run more than a couple minutes, VATS is fine. It's crazy how big a pain it is to get the gas tank in.

I know I had a little carbon in my ignition switch housing, I wonder if you've just got a switch problem? I was going to rewire last year but it's hard to work on it when it works.