Please Help With Mystery Relay X And Starter No Go

[DrAnonymous]

So I've had this issue for awhile were my 83 Rabbit decides it won't start. After two recent issues where I needed to be somewhere, I got fed up and started trying to figure out what's wrong. Here's what happens:

- If its 'hot' outside, I live in Az so your temperature may vary, it sometimes won't engage the starter.
- If I remove the glow plug relay, it almost always engages the starter.
- Sometimes it won't start even if I pull that relay. Tonight I did some testing and discovered that if I remove the 40Amp relay (its the one labeled Load Reduction Relay on page 158, section 6 of the Bentley manual) the starter engages.
- This has nothing to do with the starter itself being hot or seized or anything. Its definitely electrical.
- When the starter isn't engaging, I confirmed there is no voltage on the solenoid line. Strangely, there is voltage for just a brief instant and then its gone again. (put meter on solenoid line, turn key to start position, meter flashes voltage, then goes back to 0)

I called this issue Mystery Relay X, because thats the buss which gets powered from that relay, based on the schematic. The fuse/relay panel also labels it X.

Does anyone have any idea why either relay would have anything to do with the starter getting power? The schematic seems to indicate that the solenoid is powered from battery to ignition switch to solenoid. Those relays would only seem to make a difference if they were pulling the battery down so far that there wasn't enough power for the starter, but the lack of voltage on that line seems to go against this theory.

I'm tired of getting temporarily stranded, especially when I have my young kiddos with me. Ideas or tests I can try?

[82vdub]

I believe the "X" relay is the load reduction relay. It kills the lights, radio and a few other things when you engage the starter.

To me, with a mystery of gremlins happening at once, that leads me to believe that you've got a bad ground somewhere. If the ground goes to a "floating" situation, relays won't pull in and things won't happen as they should when there's not a definate connection to ground.

There's many ground connections behind the fuse panel. I'd start by making sure all your grounds are connected under the hood, and especially the chassis to trans ground connection. The starter mounted on the engine has to be connected to the battery ground, and that's done through the ground strap as the motor mounts are rubber and won't conduct electricity. After you've verified all grounds under the hood are good, tight and clean (to bare metal), then move to under the dash behind and around the fuse panel.

Either the ground issue, or that you may have a connection that's become loose, or frayed, that sometimes passes power and sometimes doesn't, depending on the load on it and a few other factors.

[TylerDurden]

Which tranny, Manual or auto? If auto, it is very likely a hot starter issue, usually because the heatshield is missing.

If manual, I concur with 82, likely a bad ground - but I would start with engine/chassis/battery ground connections.

[DrAnonymous]

Thanks for the info.

I tried the ground issue yesterday by clamping jumper cables from the negative terminal to the engine block. This didn't have any effect. Today I pulled the fuse panel down off its mounts and looked behind it. There were two wires screwed to a metal plate for grounding (one wire went to the brown wire of the glow plug relay) and they were nice and tight.

Its definately not the starter getting too hot. If it were, then unplugging relays wouldn't make it start working. Recall that when the starter isn't engaging, there is no voltage to the starter solenoid, which makes sense. The problem is figuring out why the voltage drops out.

Anyone have a real schematic for the glowplug relay or starting system?

[bscutt]

That could well be a corrosion problem inside the fuse box too. Sounds like possibly a high resistance connection in there and when you crank it is opening up and dropping all the voltage due to the high current draw.

Being a fix it kind of guy I would probably just rig up a headlight relay and start button to supply the actuation voltage to the solenoid via the relay. We did this on my son's Corrado as a nice aftermarket "START" button due to a flaky ignition switch body that just didn't like to go all the way to the crank position, but this works regardless of the incentive for doing so. We actually did his with 2 relays to accommodate the X relay function in the ignition switch (cuts out accessories when cranking). I had drawn a schematic for it, will try to find and post.

At least this approach would get you up and running. Beats opening the hood and shorting the solenoid terminal to the starter terminal with a screwdriver (been there...)

[Quantum-man]

Faulty ignition switch?

[Fatmobile]

If the voltage is dropping,... where is it dropping?
The ignition switch is a good place to start.
Measure at the 30 and 50 connections when the key is turned to start.

Generally turning the key to start and holding it there will cause any bad connection to get warm/hot.

[Fatmobile]

There is also something called the seat belt starter interlock relay.
You don't just happen to have your seat belt on occasionally when trying to start it do you?