Grey Relay 109 Failure

I've been fighting an intermittent no start issue for weeks on my 330K 2000 Golf. Symptoms appeared like a weak battery. Turn key on, cluster lights up, glow plugs cycle, turn key to start and clicking with no crank over. Sometimes the cluster would blank out doing this. Repeat a few times and eventually it would start. If not it would start with a jump from another running car.

Current battery was 3 yrs old so I swapped in a new one. Things were fine for a couple weeks, then issues returned intermittently.

Crawled under the dash, verified I had a grey Relay 109. My research here showed that a bad 109 would not cycle the glow plugs so I thought mine was good.

Thought it must be something else. Battery showed 12.8V at rest, 14V charging. Pulled the NEW battery, had it load tested, thinking maybe a bad cell.? Cleaned all the grounds under the battery tray, for the ECU, engine block, starter connection, etc. Thought maybe I had a dead short draining the battery while sitting?

Things were fine for a couple days, then multiple no start, dead cluster, etc. Battery metered 12.8V, but car started with a jump and drove 60miles home.

Said F it and ordered the $20 Relay 109. Swapped it out and the car fired right up.

My thinking is the 109 Relay failed internally. I've had the car 9yrs and almost 250K. Maybe a bad solder joint where it could handle some load, but not enough? Jumping from a running car would be 14V, slightly higher, but just enough to make the gap?

Relay 109 would have nothing at all to do with the cluster, or a slow crank. You could take that relay out and throw it in the trunk, the cluster would all still work (just the MIL and glow lamps would not work) and if you turn the key it would crank and crank like normal... just would not start. All the relay 109 does is power up the engine controller, that's it.

My bet is something else is suspect, possibly in the relay block area, and you just disturbed it enough to make a poor connection good again.

Well other than unplugging the big relay right below to reach the 109 above I did not move anything else. Wiring under the dash all looks good, no rodent damage, etc.

This was not a slow crank, there was no crank, just clicking when it failed to start and the cluster lights/gauges would drop out like low voltage. The clicking sounded possibly under the dash, not as loud as a starter solenoid. But when it did start all was normal like nothing was ever wrong.

Any suggestions on where else to dig?

I'd say somewhere in that relay box is a bad connection. Almost have to wiggle around on it while the key is on maybe and see if you can make it happen.

Don't think it could be an ignition switch, as you were not really messing with anything by it, but maybe? You move the column in a position that you don't normally do while you were in there getting at the 109?

No moving of the steering column, I just stood on my head.

Is there a main relay that is triggered by the ignition switch that could have worn contacts? This would not flow enough power for the ECU and Starter Solenoid?

If it was going to act up yesterday and today were cold and damp which always seemed a factor over the last few weeks.

If it's fast clicking it could be a bad connection in either battery cable.
Maybe take a few minutes to clean both posts & clamps, the ground under the battery box, ground on the trans, and the positive cable at the starter.
You might look at the wire going into the starter at the lower solenoid terminal. They are known to corrode.

He already cleaned all the grounds and battery cables!

There's no relay for the starter solenoid.

Did you check the fuse panel on top of the battery? Make sure it is clean and each of those red wires and their corresponding fuse link connections are clean and making proper contact. Those circuits provide power to all the things inside the vehicle. One of those provides the power that goes to the ignition switch (and other places), which in the start position, provides the power to the Starter Solenoid! The bigger black wire on the left (looking at the fuse panel from the front) goes to the Alternator.

Any one have a guess on the Ohms, etc a 109 Relay should meter out as? I've got a Fluke I could check the contacts with? That would rule it out?

I checked all the fuses/links on top of the battery. Pulled the 3 blade fuses and reseated them a few times. Nothing looked corroded there. I cracked all the nuts loose for the fusible links and retightened them.

The only green crusty corrosion I found was the center connection in the NEG cable from the battery where it grounds under the battery box. JUST CORROSION along the cable where the insulation is off for the chassis ground. The actual ground tab and the post itself was clean. The connection at the engine block and battery both were clean.

Maybe a new set of POS/NEG Cable is in order after 18yrs?

Again, 109 not related to your symptoms, at least not electrically. And you've already shot-gunned it.

It certainly sounds very much like an intermittent connection problem somewhere in the large cables downstream of the battery... which has enough resistance to cause the system voltage to dip to 0 under starter load, blanking the cluster, clicking some relays, etc.

When it won't crank the next time perhaps pop the door open and see if the dome light still comes on... and what happens to it when you turn the key again. Having your Fluke monitoring battery voltage, say at the cig lighter, would be even better.

For sure big ground connection at the transmission is OK? Battery connections clean enough to eat off of?

Vince Waldon said:

It certainly sounds very much like an intermittent connection problem somewhere in the large cables downstream of the battery... which has enough resistance to cause the system voltage to dip to 0 under starter load, blanking the cluster, clicking some relays, etc.

Click to expand...

Key in, turn the ignition on: this is where the cluster would sometimes drop out and you'd hear a buzzing. If the cluster came on, glow plugs cycled, and then turn key further and attempted to start: then the clicking/buzzing, cluster drops out, radio went in safe mode, etc. Repeat this process several times and you might get a normal start.

Battery metered at 12.8V resting during all of this over a few weeks. Was always able to get it started with a jump from a running car, not always with a 2nd battery. Thats what makes me think its voltage related - 12V vs 14V.

Since I cleaned all of the grounds and topside battery box connections (which looked fine, still shiny under the fasteners) and swapped the 109 its been good for several days. Gremlins?

Ok, that now makes it sound more like an intermittent ignition switch (the electrical portion of the switch as opposed to the tumblers).

The ignition switch is definitely a wear item and a not-uncommon failure as our cars get older.

Oh, and both cheap and pretty easy to replace.

JPinnell said:

Maybe a new set of POS/NEG Cable is in order after 18yrs?

Click to expand...

Only if they are bad.
They -might- be corroded internally.

Two simple voltage drop tests.
Measure from the battery positive post (not the clamp) to the positive stud on the starter solenoid. (not the cable)
Have someone crank the car. I would not want to see more then a few tenths of a volt.

Same from the negative post of the battery to the case of the starter.
Same few tenths of a volt.

Last with the lights and key on measure the voltage across the fuses on top of the battery, this time on the wire terminals. AndyBees has a good idea there. Sometimes the fuse gets a bad (or loose) connection.

JPinnell said:

Key in, turn the ignition on: this is where the cluster would sometimes drop out and you'd hear a buzzing.

Click to expand...

This is the part that now has me thinking ignition switch.

If the cluster was fine with the key in ON but dropped out when the key was turned to START I'd suspect a bad connection in the heavy-duty cables between the battery and the car, and yup would go looking for it with a voltage drop test... if a physical inspection turned up nada.

^^^ I concur.

Ignition switch OR the connector shell on the back side of it, and melted or burnt wire ends going into it. Which for some reason seems to happen more on Beetles, but I have seen it happen on Golfs and Jettas too.

Have to buy a new connector shell and all the repair pigtails and carefully cut and splice the new ones into the harness.... the whole time making sure to make the repair so that you can fit it back under the steering column cover. A tedious process, but I've gotten good at it.

That type of thing is usually not intermittent though.

Could also be a bad connection in the cluster. A scan tool may reveal some clues in some of the modules... if something has stored a DTC for loss of communication, for instance.