Hello Bricksters, I've done the obligatory searches and this one might just be too weird... On occasion I've gone to start my 240 and when I turn the key, the usual "idiot lamps" will not come on. Instead the overdrive arrow light comes on and the car starts / runs normally. The fuel / temp gauges will be dead too. I shut the vehicle off, turn the key to the 2nd position and then turn the headlights on and off a couple times. I can't remember how I stumbled onto this "fix" but for some reason this action will turn the lamps back on. I can then start the car, and the lights will go out as they should. What I'd like to know is the headlight switch a red herring or is there something to this? Is the main dash power through the headlight switch? Does the daytime running light relay have something to do with the interruption to the power to the dash?
The car works great otherwise. Thanks and looking forward to some insight!

My 89 240 just started doing exactly the same thing, even the part about curing itself, sometimes, when I move something to the left of the panel, like the light switch, or the fog light switch or the interior light rheo. I also have no speedo or tach. When the problem occurs, sometimes I can turn off the OD arrow with the shifter button, and sometimes I can't.

My problem started right after I had the instrument cluster out of the car about 10 days ago. My initial thinking was that, since it affects many of the instruments, it must be a ground. I have not yet had a chance to investigate.

I'll get in there this weekend, and get back here with whatever I find.

Box, it sounds like your problem is the little strip fuse that goes across the top of the speedometer. You might need to check and make sure the contacts that go under the little screws are making good contact. That fuse is supposed to prevent a short from burning up the instrument cluster. If it does make good contact you will have a dead dark instrument cluster. And your Alternator will also not charge with no power on the cluster.

Regards,

Paul

Thanks, Paul - further down, Art Benstein suggested the same thing. I had the speedo out right before the problem started, so that possibility went to the top of the chart.

Interesting indeed. I don't have a tach and I've yet to drive with the lights out so I don't know about the speedo... but I wouldn't doubt it at all. I haven't had my speedo out, but I did install a stereo earlier this summer... hmm, I think I need to have a look under there too.
Thanks for the suggestions guys!

I don't know if this helps at all, but that sounds like what happens when I disconnect my battery for a while and then reconnect it...
--
'85 240 wagon, '86 ford pickup

It sounds like you need to check the ground wire on the Alternator. The wire gets eaten up, and that is the symptom of the problem. Blue wire that goes to a bolt on the bottom side of the engine and over to the alternator housing. If in doubt, change it out. If it does open up, the alternator does not charge, the warning light does not come on, and you find yourself with dim headlights and going slower and slower. Many a 240 owner has replaced a good alternator because of that wire and then wondered why the new one did not work any better than the old one. The AC Compressor and the Alt both need a chassis ground and they are riding up on those rubber or poly accessory bushings. The Connection from the Block to the body is the only way either get to chassis.

The other thing to check is make sure little red wire is firmly screwed to the alternator.

With the Key in II, the warning lights all light up via the little red wire and through the Alt housing to chassis. Quick test you can do is to put the key in Pos II and then hold a wire from the housing to the engine block. Have someone look a the lights and if they pop on when you make the connection to chassis, that is the problem.

Be careful, don't let a hand wander around with all that current on the big red wire. If is just waiting for a ground to pass by and that would not be any fun at all.

Good Luck,

Paul

I notice that you have more than one posting regarding the infamous gray connector where the thin red wire comes from the alternator. The wires on the driver side are in good shape, on the passenger's side not so much. If I chose to wire around the connector, is it red to red, yellow to yellow etc? Also i think I read in one of your posts that you spliced into the red wire and ran it to the alternator. Did you splice into the passenger side or the driver's side? I tried splicing into the the red wore on the driver's side and no go.

Thanks

Two months ago, I had all the lights come on while driving. I recognized the problem and I cleaned up the red wire and while I was down there, cleaned the blue for good measure. Problem solved? maybe?
Interruption of power (red wire) provides the ground for the idiot lights to illuminate. Check.
Interruption of the ground (blue wire) interrupts the power to the lights. Check.
The overdrive light coming on suggests the power has been cut to the overdrive solenoid. Yes?
The overdrive light coming on suggests there is power to that lamp. Yes.
Provided the overdrive lamp is powered by the same circuit as the rest of the lights then grounding seems like the logical issue with the other idiot lights (overdrive light grounded through solenoid).

So, I will tackle the blue wire again and try the jumper too.

Does this make sense Paul?

...to consider besides the warning light circuit. An Ignition Switch problem might also account for the Fuel and Temp gauge problem and the "OD light" that's On when it should be Off.

Interruption of power (red wire) provides the ground for the idiot lights to illuminate. Check.
[Part of the ground path. See blue wire.]
Interruption of the ground (blue wire) interrupts the power to the lights. Check.
[No, it opens ground path from the lights, same as red wire.]
The overdrive light coming on suggests there is power to that lamp. Yes.
[YES, but that power is separately hard-wired to the panel at push-on terminal 34, Yellow-Red wire.]

The overdrive light coming on suggests the power has been cut to the overdrive solenoid. Yes? Actually "No".

The Upshift Arrow light ON means no power to the OD relay, which should be automatically energized when the Key is turned on. The Arrow bulb voltage is hard-wired (see above). The ground side is thru the (de-energized) OD relay.

1) The source of this missing power at the OD relay is a Blue-Black wire from Fuse 11. Fuses 11-12-13 get their power via Blue-Yellow wire from Ignition Switch terminal 15I.
[Check for +12V at the LEFT (common) side 11-12-13 fuse contacts with the Key On.]

2) The power for failing Warning lights, as well as the Voltage Regulator for the Fuel and Temp gauges, comes directly from Ignition Switch terminal 15 via a Blue wire to Instrument Cluster terminal 233/3 (see 3-pin push-on connector at the back of the speedometer).

Ignition Switch terminal 15 circuit also powers Fuse 5 for Turn Signals and Backup Lights.
[Check for +12V at the LEFT side fuse 5 contact with the Key On.]

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

From what I'm reading, if the turn signals and backup lights are working, the problem is likely not the ignition switch terminal 15? And if both sides of fuses 5, 11, 12 and 13 are hot in KP II, then the problem is elsewhere?

In my case, I'm going to look at the three pin connector, simply because I had it off recently.

In addition to the 3-pin L connector - a common trouble spot - there's a "flex fuse" on the back of the speedo held in by two small screws. If some work was done on the speedometer gauge, these screws and their electrical connection to the fuse may have been disturbed.


--
Art Benstein near Baltimore

Growing old is mandatory; growing up is optional.

... er, the flex fuse. Or perhaps the three prong connector.

I had the speedo out a little while ago, and did not tighten down one of the screws on the strip all the way.

Or perhaps the three prong connector - when I re-installed the cluster, I made sure it was securely fastened.

Thanks for the help to everyone.

By the way, when I was in there, I found a yellow wire with a spade connector that did not seem to have a home. Any ideas what that might be?

Ah, another likely suspect, maybe the most likely. I had the speedo out.

You are a gentleman and a scholar, sir.

What exactly is the "flex fuse" protecting?

Overdrive Light is not part of the bulb check. They do get voltage from the same place but that light switching on and off does not mean anything but you have power to the dash.

The bulbs in the circuit are the Brake, Alt, Oil Pressure. The red bulbs only light up if the red wire is connected and the chassis of the Alt is grounded.

Regards,

Paul