No Start - Electrical Problem

[gsbarry]

Stock 97, 4.0 SOHC EB

I'm having trouble diagnosing the cause of an occasional no start condition (roughly 1 in 20 starts).

It's definitely electrical, when a no start condition occurs I can always jump the solenoid from the battery and start that way.

I have a good battery, starter motor, and starter solenoid fender relay (replaced twice to be sure).

My original thoughts were that it was a battery cable going bad, but I am getting correct voltage readings on the roughly 8" ground wire from battery to frame, as well as the cable going from the positive battery terminal to the solenoid relay (both showing 12.6 volts during the no start condition).

The red ignition wire is always showing 4 volts whether or not the ignition switch is in the 'on' position (I thought this was odd - i assumed there would be not voltage to that wire when in 'off'. Maybe it spikes to 12 volts when starting in order to activate the solenoid relay...).

I have noticed two different effects from the no start condition.
In one case, there is no sound (no starter motor turn, and hence no engine turn) but power remains to the rest of the vehicle after key is released from 'start' position (and in either 'on' or 'off').
In the other case, when attempting to start I hear a single click (sounds like a fuse popping - but all the fuses are good) (again no starter motor turn, and hence no engine turn) and then the vehicle loses all power in any key position. I can only resolve this case by disconnecting the negative battery cable (it must reset something though I'm not sure what), then jumping the starter solenoid relay. There is no blinking of the anti-theft light.

I should also point out there is no CEL (no codes), and no other issues.

I am not sure about where the other negative battery post wire goes, or the other two wires connecting to the 'always hot' post on the solenoid relay. What I mean is I'm not sure where they go or come from, so haven't been able to test those. That being said, it is a southern vehicle and all the wires look decent, but you can never be sure I suppose.

Sorry for the long post, but I thought it was all relevant.
I am out of ideas for now, help would really be appreciated. Thx.

 

[yavapaires]

Sounds to me like a worn out ignition switch. Do you have a Haynes or other repair manual? If not, the switch is located under the dash, has an actuator rod from the lock cylinder to the switch.

 

[2000StreetRod]

4 volts?

. . .
The red ignition wire is always showing 4 volts whether or not the ignition switch is in the 'on' position (I thought this was odd - i assumed there would be not voltage to that wire when in 'off'. Maybe it spikes to 12 volts when starting in order to activate the solenoid relay...).

Are you referring to the red/light blue stripe wire that goes from the ignition switch to Fuse 24 in the interior fuse panel? If so, it should be battery voltage in Start and no voltage otherwise.

There's a red wire from the battery + terminal to the starter motor and the starter relay. That should always be battery voltage.

There's a red/light green stripe wire from fuse 19 in the interior fuse panel to the PCM power diode and the ignition coil. That should be battery voltage in Run and Start.

Try to start in Neutral instead of Park the next time you have a problem. Your shift linkage may need adjusting or you could have a bad transmission range switch.

 

[yankups]

I'm pretty curious about this myself, I have a 99 exp XL and basically the same issues, except I haven't tested any of my cables the battery has been tested and good. In fact just friday morning it wouldn't start again my neighbor came to jump it...nothing, he moved jumper cables i could hear it spark i all of a sudden got the theft light flash for a second, it finally sounded like it was trying to start. He moved em again and it started sparking at post and it started right up, no issues. I got to work no battery to even lock doors. When leaving work had friend jump nothing i finally said hey try getting some spark on the post when we did truck started. I got to next location, got it to lock, went to leave wouldn't start, got wrench out went and started hitting negative post & cable on battery and no spark, when I finally got a spark I tried and it started, so I'm not sure if it could be the cable itself, the metal connector on cable to post or what, so any more info from anyone would help me too.

 

[gsbarry]

Update: I replaced the ignition switch, but still have the problem. I'll try the neutral suggestion next... if that doesn't work I'll start replacing cables.

 

[yankups]

Update : I ended up replacing the negative battery cable, the complete ground and all about 2 months ago, I thought that might solve the problem but apparently it didn't, I have had it not start 2 times since - 1st time on a friday night hit it with a wrench a few times, started right up, the 2nd time was a week later on a friday night this time it wouldn't work by hitting it, had to jump it which started right up, haven't had the issue since but i'm sure it's gonna happen at some point

 

[budwich]

doesn't sound like fun. You need to find out what you are chasing.... a poor battery/ground connection at the battery or a poor connection "further" in the system. When you have the problem, are you able to turn your headlights on AND are they "well lit" (ie. not "dimmish")? Further, when the system doesn't work, do you hear any clicks in terms of relay operation. I would be carrying around a meter in the vehicle to help gather more info.... it won't likely get you started any faster (maybe if you test the "right point") but it may help you resolve your issue once and for all.

Of course, one of the first tests when its "broken" is to check if there is voltage after the interior fuse (24?) during the "key in start" position.

 

[gsbarry]

I took a look at the wiring diagram. Given that I have already replaced the the starter relay and the ignition switch, and don't see an anti-theft light... it looks like my list of possible culprits are the transaxle range switch, a faulty wire somewhere in the circuit, or the 'starter clutch pedal position jumper'.

Does anyone know where the pedal position jumper is located? (cabin side of firewall area maybe) Or what it looks like? The wiring diagram shows that there is a 'jumper' on automatic trans and a switch on manual trans. I have an automatic, but am a little confused at the name since there is no clutch pedal on an automatic - I guess this just means that it 'jumps' the location where it you would have it on an automatic.

I have been carrying a meter and am checking components progressively, but am little new at electrical troubleshooting, so I feel like I am fumbling around.

 

[budwich]

"been carrying a meter..." sounds fine and good BUT you need to use it. Can you actually tell us that you have voltage after the fuse (24 maybe in your year).
From your posts, it would appear that you have been focusing your efforts before that BUT I don't think you know why as supported by some "real testing".
Until you are certain of the conditions at various stages along the circuit path, you are just "guessing".

 

[gsbarry]

I hear you Budwich on actually using the meter...

The problem is that the no-start condition occurs one in fifty starts and I rarely, if ever, have a helper with me to turn the key to start while I hold the meter leads.

So for now I am just guessing... as long as the parts aren't too expensive I'm okay with that.

So does anyone know where the 'clutch pedal jumper' is located? Or what it looks like?

 

[budwich]

BUT .... the interior fuse is right there by the steering???? get some alligator clips (one at least for the ground side test lead so that it can be "permanently" connected OR put some sort of wire on a ground point that you can readily connect to). The rest is well "easy" for a "pair of hands". Anyways, good luck on the "ghost chase".


Heck, with some "prep work", You can probably easily connect up your meter "permanently" somewhere along the circuit path and just turn it on when the problem happens... "look mom no hands"...

 

[gsbarry]

I'm pretty sure its the transaxle range switch. I was just about to check fuse 24 when I tried to start in Neutral and it started nicely.