Won't start in park, starts in neutral

[mike123]

+1 on following G:05:02.
WRT to the starter, the only difference in Park and Neutral is which of two cam lobes presses one of the buttons on the multi-function switch inside the transmission. It would be rare for the cam or switch to have a problem.

Joe's issue was that the car would start in Neutral but would not start in Park... but what if it won't start in either Neutral or Park? Would that indicate it might be the cam or microswitch?

[jangell]

Joe's issue was that the car would start in Neutral but would not start in Park... but what if it won't start in either Neutral or Park? Would that indicate it might be the cam or microswitch?

That does sound like it's somewhere in the start inhibit circuit. I'd probably start by testing the relay and its socket in the relay compartment, since that's likely the easiest place to do a quick test form.

-- Joe

[mike123]

Sorry, I did mean to provide some additional info. Yes I tested the relay and socket and the white/yellow wire female spade does not have ground (like I think it should) when I am having starting issues. The relay itself is only a few months old and swapping it made no difference. In all testing, the shifter has been clearly in Park or Neutral as best as one can be certain from the driver seat.

In reading some advice on Facebook again (things make 10% more sense each time), it seems like it could be the switch but could also be the bulkhead connector (which looks clean to me) or the connection to the switch. So I guess I will try to test those things before assuming it is the switch itself.

[mike123]

Wiggling the bulkhead connector actually worked! The car started after I wiggled it.

I notice that the male end of the red connector (which contains the yellow/white wire that is causing me all the problems) is different than all the others:
11-13-23 bulkhead connectors trimmed.jpg

Interestingly I have only found four other close-up images of this connector on other cars. VIN 16028 has the same red plug style as mine, as does maybe Joe's (see below), and another car (VIN unknown) and the DeLoreanTech YouTube channel car, have a red plug that matches all the other plugs, e.g. clips with holes in them and a rim around the male piece.

And Joe, your red connector appears to be the same style as mine, but maybe in a different position: https://www.tmproductions.com/repair...head-connector

[jangell]

Well, I have an EFI conversion, so I packed all the old wires into the large Deutsch connector in a custom bulkhead plate (basically a piece of plastic that I heated so I could put a 90 degree bend in it to replace the original metal plate). The automatic transmission and tail light connectors are the only original connectors still there, which is why it's in a different position.

I also have an early VIN (767), but that doesn't seem to explain why my connector might be different, since you cite other cars with later VINs having the same connector. I think they're functionally the same, just that there's an extra lip. I might help with weather sealing a little.

Still, these connectors aren't not the greatest Some kind of conductive grease on the pins might help (not dielectric grease -- that's an insulator), or you could remove the female connector, remove the pin, and carefully crush with pliers it so it's SLIGHTLY tighter. It is easy to damage it by oversqueezing, though (there's a point where it feels like you're not crushing enough that suddenly becomes the point where you've crushed it completely), though, plus it's not that easy to get the pin out in the first place.

The hack option is to jump around it. Say, adding a short run of wire with a spade connector to the relevant wire no the connector, which would plug into another wire on the back of the bulkhead connector. But that's pretty ugly and I'd probably leave it as a last resort (say, after you ruin the female pin by trying to crush it).

-- Joe

[mike123]

Eyeballing the connector and the extremely minor movement that led it to go from Not Working to Working also makes me wonder if the loose connection is further down the line of the white/yellow wire. And maybe wiggling the red connector really just wiggled the wire at the actual problem site.

My usual and very amateur method for loose friction pins is to just put a thin coat of solder over them, but the pin here seems fine. It is either the red plug is not going in far enough, even when clipped... or the problem is further down the wire.

The car is going to Crystal Lake next month, so there may be something obvious that they see that I cannot. And until then, I now have 3 ways in my repertoire to solve the no-start problem:

1) wiggle red plug while someone turns the key
2) jump the starter relay with a little double spade wire
3) jump the starter itself by giving it electricity via jumper cable

Still, I will be very excited when/if this issue can be definitively found and fixed. It is the only issue I have had with the car so far.

[Bitsyncmaster]

Eyeballing the connector and the extremely minor movement that led it to go from Not Working to Working also makes me wonder if the loose connection is further down the line of the white/yellow wire. And maybe wiggling the red connector really just wiggled the wire at the actual problem site.

My usual and very amateur method for loose friction pins is to just put a thin coat of solder over them, but the pin here seems fine. It is either the red plug is not going in far enough, even when clipped... or the problem is further down the wire.

The car is going to Crystal Lake next month, so there may be something obvious that they see that I cannot. And until then, I now have 3 ways in my repertoire to solve the no-start problem:

1) wiggle red plug while someone turns the key
2) jump the starter relay with a little double spade wire
3) jump the starter itself by giving it electricity via jumper cable

Still, I will be very excited when/if this issue can be definitively found and fixed. It is the only issue I have had with the car so far.

Get a mating pin and crimp it on a wire. Then use that pin to feel the tension pushing and pulling the pin in and out of each mate. You would be surprised of the difference between a good pin and bad one. Do it for the relays and the bulkhead.

Now there are also bad crimps. To find those you wiggle the wire to test. Better if you can do it while the problem is powered.

[mike123]

That is a good suggestion, thanks Dave. I will try that with the pin. And regarding the crimp, I may be able to eyeball that or wiggle-test it.

EDIT: Actually on the crimp side of things, I ordered a $7 pin removal kit on Amazon. I should have one anyways I guess. But that should allow me to pull out that yellow/white wire pin and take a close look at it.