Hi all

My D2 has intermittent turn signals. Until the last few days this winter the turnsignals would sometimes work and sometimes not, if it didn't work I could typically push a little harder on the stalk and it would start working.

The turn signals finally stopped working all together the other day. This pointed me towards the switch being bad, combined with the cold weather we've had in the Midwest. Today I disassembled the turn signal stalk switch and cleaned all the contacts. To be honest the contacts didn't look horrible but were a little dirty.

Upon reassembly and reinstallation the turn signals are still not working. I've also checked fuses and confirmed theyre all intact.

I can buy another turnsignal stalk if need be, but I'd prefer to determine the switch is really the issue.

The other idea I've had is maybe it has a bad ground. Wet and cold winter here, maybe moisture in the footwell has corroded the ground? (After thinking more, maybe not unless the plugs in the socket aren't making contact I think a bad ground would affect more if it was a common ground point) Does anyone have a photo of the ground location for the turnsignal switch? I haven't diagnosed electrical issues much before, but have a multimeter I can use.
Additional Information: The hazard light switch still functions and I can confirm that all turn signal lights are functional.

 

This was solved:

I tested for continuity on the switch to the prongs and confirmed continuity was good (before this I added a shim between the shim and copper)

Then I tested for continuity at the connector, there was no continuity. I adjusted the prongs gently ( they're very soft) and tested for continuity again by backprobing. Confirmed continuity, started the truck up and no turn signals! I put it into drive, backed up a few feet then pulled forward and tried using the turn signals and they worked perfectly. I wonder if the BCU doesn't allow turn signals after startup until the truck is moving?

IF someone runs into this again I would save time by testing for continuity at the connector to the turn signal switch first

If that fails remove the switch and test for continuity at the prongs.

If that fails open up the switch and clean all contacts, test possibly shim between the springs and copper contacts with some aluminum foil

Reverse continuity test

IF failing again at the connector from BCU to prongs from switch then attempt to adjust the prongs to allow better contact (Gently!)

 

Unfortunately the issue returned the other day.

I'm thinking there is an issue with one of the IGN circuits. I've noticed when the turnsignals don't work its also when the cigarette lighter does not work. I haven't confirmed on wiring diagrams yet that this is the case.

Confirmed I have continuity at the turnsignal switch and the connector still.

I need to test continuity at the ignition switch, but its been mighty cold in Wisconsin the past week. Besides testing the ignition switch, where else would one troubleshoot? I checked the fusebox looks corrosion free as far as I can tell.

 

I came across a similar issue where there often was a delay in the turn signals operating. Sometimes they worked straightaway, other times there was a 2-3 second pause, or 5-6 seconds, whatever. Sometimes the one would come on immediately but when I went for the other moments later it would delay. Never repeatable in any sense, temperature, run time, lever pressure, none of it mattered. I swapped an interior fusebox but no change so I assumed BCU. When I got the truck ('99 SE7) the windshield cowl was a disaster so water permutation could have been an issue. I ended up selling it a few months ago without knowing the cause but I'd be very interested in learning what you find out, as I one day may get it back.

 

I vote interior fusebox. There is a soldered in relay in there for the turn signals, I believe there are 2 (oddly, one is Left, one is Right).

 

That would be the logical conclusion, and what I would try next if I were the OP. Just for the added troubleshooting info, in my case I put a known good fusebox from my 2000 into the 99 and the problem did not change.

Here's the quote from the RAVE regarding operation of the turn signals.

The direction indicators and hazard warning lamp operation is controlled by the Body Control Unit (BCU), Intelligent Driver Module (IDM) and two electronic relays in the passenger compartment fusebox. The IDM and the relays are are an integral part of the passenger compartment fusebox and cannot be serviced individually. The direction indicator circuit uses the serial data bus between the BCU, IDM and the instrument pack for flasher and hazard request and operation.

The only common link between the cigar lighter and the turn signals is Fuseable Link #8 in the engine compartment fusebox. That passes voltage through the interior fusebox and on to the ignition switch, which then energizes BCU through Fuse 29 when the ignition is turned on. Interior lights are another circuit on Fuseable Link #8 and if those function then you can rule that out.

The RAVE shows that the stalk sends ground to the BCU at C0660-6 & C0663-2, depending on which side is called for. The BCU then converts the signal from simple continuity to serial data. The data travels to the interior fusebox and lands at Pin 6 of the IDM. After the IDM translates the serial data we're back to simple electrical connections. The two internal relays are always hot at pins 86 (coil) and 87 (switch). The IDM passes ground at Pin 2 for left or Pin 21 for right to energize the coil side of the relays, which supply the switched voltage back to the IDM at Pins 11 or 13. The IDM sends voltage back out Pins 10 or 12, which are connected to the lights themselves.

As the OP, my hazards worked normally. The only difference there is where the input signal to the BCU lands. The Hazard switch hits Pin 12 of C0663, instead of Pin 2 (left) or Pin 6 of C0660 (right) from the stalk. After the serial data travels from the BCU to Pin 6 of the IDM, all other circuits are the same with regard to lighting the actual bulbs. It appears that based on that serial data, the IDM passes ground to either Pin 2 (left) or Pin 21 (right) to energize the individual relays, or grounds both relays at once for hazards. If the hazards are functioning normally, to me this says that the internal relays and the rest of the circuit are good and it's either the serial data signal coming from the BCU or the IDM itself. Without a schematic of the IDM it's impossible to know what's happening inside there so swapping the fusebox has to be the next step. If not that, then the BCU would be the only other possibility. One interesting wrinkle is that the BCU sends the serial data to Header 0293, where it splits and goes to both the IDM and the cluster. I'm not sure if a faulty IDM would mean that the cluster lights would work but the indicators themselves wouldn't, but it seems like this might be the case. Maybe a Nanocom might help sort this out.