[E34] Electrical gremlins after some time standing still

[Frank87]

Hey guys.

I brought the E34 to Poland in march for full body restoration. I want Alkyd paint and for that I had to go to eastern europe where the interpretation of the law is very liberal.

Car body is 100% perfect. Total respray and restoration. I picked up the car and drove home. I have 2 issues now that were NOT there before:

- the instrument cluster has working fuel / temp / speed / rpm meters but the digital displays under it do NOT work. Also, the gong does NOT work if I purposely sabotage a light. So:
= I don't see the mileage / odometer
= I don't see any warning message neither do i hear the gong
= I don't see the A D automatic indicator
Not even the lighting of the bottom part works. Its just black as if the car is turned off

- the heater can only blow at maximum hot. Neither the A/C nor the regular "cold outside air" mode works. The heater valves were replaced in january with a brand new part.
- rear window defogger does not work. Press the button, the led will shine and then immediately turn off
- A/C doesn't work. Compressor can't be turned on
- AUC / recirculation doesn't work. Press the button, the led will shine and then immediately turn off


Anyone got any idea on the above issues where to get started? I plan to remove the heater valves and put 12v on the 3 prongs to test if i can hear them click or move. That takes care of the heater valve functioning.

I will also take the cluster apart to check for bad components on the circuitboard but something tells me the problem won't be there.

The A/C system has been full for the past 3 years. I have it checked each summer but they remove a 99% full charge every summer. I don't believe the A/C would be empty. I have replaced all A/C parts and rings a few years ago.

I have already checked all fuses and all relays. Also under the back seat.

[whiskychaser]

With regard to the cluster, have you tried shining a torch at an angle on it? It is possible that the displays work but there is no backlighting.
The heater valves default to open so it sounds like the controls are not working. Same with the demister and AC.

I would start with the wiring diagrams

Was the dash removed for paint?

[Frank87]

Dash was not removed.

Heres the status:
- opened the instrument cluster. Replaced all bulbs just in case. No bad soldering. No bad components on the boards.

- experimented with a spare IHKA computer( the one with the 3 colored connectors). Same problem.

- removed the auc sensor and module just in case. Same problem.

- used a computer to read error codes. No errors other than a stratification potentiometer which has been in there for years. All sensors of the IHKA read good values except the interior temperature sensor which reads 60 celsius permanently.

- did whiskeys thing by shining at the lcd display. Odo and P D appear to display properly but with no lighting. The center bar shows an error "check control betriebsanleitung".
- removed the ccm module, checked it out and put it back in. Same error. Looking for a replacement ccm now.

Parts im getting soon are CCM.. spare manual A/C control panel and the parts required to fix the interior temp sensor.

Will let you guys know.

[Frank87]

Checked A/C parts near the dryer. Connectors were in bad shape and some wiring broke off upon touching it. Totally fishy.

Resoldered everything. Both pressure switch connectors are now rock solid. A/C compressor plug also resoldered and strengthened.

Still no A/C. I am sure the A/C hardware is now in good shape. I will continue once I have those modules in.

[Frank87]

Had some modules to do some testing. CCM, LKM, GM5 and IHKA modules. 4 of each, no joke.

Swapped them all 1 by 1 and tested, nothing improved. My defroster, A/C, recirc and auc are still not working and the blower only gives hot air.

I have one more swap to make and that's the control panel itself. In addition I am going to check some ground points to make sure I don't have a grounding issue.

[632 Regal]

343 lookers so far at this thread. I have absolutely no idea what's going on but tune in daily to see what you find.

[Frank87]

I checked out some ground points and some areas where theres alot of cable. Nothing found. I have absolutely no clue now where to look.

Every module associated with the IHKA and general car stuff has been swapped. No change.

The problems:
- cold air doesnt work whether A/C button is on or off. IHKA blows hot only
- A/C doesnt work, there is no way to get the compressor going. System is leak free and full. All wiring resoldered where needed
- rear window defroster does not work at all
- check control on the instrument panel does not work. Bottom bar does not light up and if you shine with a light it says "Check Control, Betriebsanleitung"

I am going to take a break from this for a few weeks. It drives me nuts. I'll focus at some small mechanical things and drive the E39 daily.

[632 Regal]

Does the AC work if you jump it?

[Frank87]

Does the AC work if you jump it?

Fine idea!

I will jump it by jumping the relay. I think it will work as the system has pressure and keeps pressure. However, if the flaps in the interior do not work and if the interior does not close the heater valves, I wont be able to get legitimate cold air inside.

Ill let you know what happens.

[Frank87]

Before:
- experimented with a spare IHKA computer( the one with the 3 colored connectors). Same problem.
- removed the auc sensor and module just in case. Same problem.

Update to this thread:
- I have replaced the DME, no change
- I have replaced the Check Control Module, no change
- I have replaced the A/C control panel with an identical one, no change
- I have replaced the 3 buttons defrost/AC/AUC panel, no change

Problem still remain:
- cold air doesnt work whether A/C button is on or off. IHKA blows hot only
- A/C doesnt work, there is no way to get the compressor going. System is leak free and full. All wiring resoldered where needed
- rear window defroster does not work at all
- check control on the instrument panel does not work. Bottom bar does not light up and if you shine with a light it says "Check Control, Betriebsanleitung"

I have a total IHKA rebuilt. Going to swap it in a month or 2. Meanwhile I keep checking the electronics as I work on the car.

[632 Regal]

Before:
- experimented with a spare IHKA computer( the one with the 3 colored connectors). Same problem.
- removed the auc sensor and module just in case. Same problem.

Update to this thread:
- I have replaced the DME, no change
- I have replaced the Check Control Module, no change
- I have replaced the A/C control panel with an identical one, no change
- I have replaced the 3 buttons defrost/AC/AUC panel, no change

Problem still remain:
- cold air doesnt work whether A/C button is on or off. IHKA blows hot only
- A/C doesnt work, there is no way to get the compressor going. System is leak free and full. All wiring resoldered where needed
- rear window defroster does not work at all
- check control on the instrument panel does not work. Bottom bar does not light up and if you shine with a light it says "Check Control, Betriebsanleitung"

I have a total IHKA rebuilt. Going to swap it in a month or 2. Meanwhile I keep checking the electronics as I work on the car.

Jump the hot lead to the compressor and watch it work. If not then you can trace it. If it works you can trace it. Not sure if I am missing a whole lot here just reading along.

[genphreak]

Jump the hot lead to the compressor and watch it work. If not then you can trace it. If it works you can trace it. Not sure if I am missing a whole lot here just reading along.

Often the AC compressor will only come on in run IF there is enough gas in the circuit. A good way to check is to get a refill can, tap and gauge pipe, seat the can on a scale, and attach it to the low side (blue) and see if there is any pressure. If you open the tap to introduce fresh refrigerant, be sure to note the mass the can loses, that way you know how much goes in. Sometimes as little as 30g will return the system to pressure enough to allow the low pressure switch to open and the compressor to engage. I have one that needs 50g every few years... I really need to replace the o-rings, oil and gas afresh, but I am not sure I'll ever get the time

[632 Regal]

I have a can of https://i5.walmartimages.com/asr/743d8edd-38fb-4f5e-96c1-569b29e65c5a_1.83adef8affc0006f1231bc618a87b41d.jp eg?odnHeight=450&odnWidth=450&odnBg=ffffffI have not used and sitting on my desk. Debating weather to spend another $32 bux for little cans or get the mega jug for $130. I could have paid for the mega jug already. If it leaks out I have plenty of reserves ready plus maybe make some back filling other peoples stuff. I have all the gauges and stuff to legally do it.

[Frank87]

I have fixed this problem.

I have:
- completely rebuilded an IHKA unit using 2 spares. Out of 3 big IHKA boxes I made 1 very neat, very clean and very good insulated (cut fresh insulation) one;
- fit and installed the above mentioned IHKA and checked all wirings, connectors and ground points;
- used a IHKA computer that was a guaranteed run on another E34 with similar IHKA;
- replaced a blown fuse. The fuse was not related to the IHKA (according to the schematics);

I now have:
- working rear window defogger
- working OBC
- NOT working mileage/automatic cluster (probably bulbs!)
- a working A/C;
- a working "hot" heater in 3 areas;
- a partially working cold heater (1 area cold only). The middle vent shafts blow cold, the window and foot ventilation keeps blowing warm/hot;

Anyone have any idea how window/foot area is separated? Could it be that one stepper motor that I put back is bad?

Either way, I got my A/C back and turning off window/foot area, car blows cold.

[shogun]

I assume (not sure) that the E32 IHKA is the same function, here are good pics and info what which stepper motor does http://bmwe32.masscom.net/johan/ihka/ihka.html
pdf Klimaautomatik German language http://www.e38.org/e32/klimaautomatik.pdf

[Frank87]

My final problem, the A/C / cold outside air not blowing at feet and windshield was the passenger water valve not being actuated. I have remade/resoldered the wiring from the harness onto the water valves.

All works perfect now. I still do not know what the original problem was but since I have also removed wiring to the A/C compressor that should not have been there (completely non BMW wiring bypassing relays) and have used a 100% intact harness from a wrecker, I think whatever problem I had is now gone.

EVERY electric thing in the whole car now works exactly as it should. No error messages. No error code except for the aux. water pump which I have removed myself.

[genphreak]

Great news.

Have the capacitors in the cluster been replaced? These will need to be done, if they haven't been. Not sure if the shut down the bulbs and doubt it, but if not, it will be a dry joint or a connector. Perhaps try looking- with the cluster apart and plugged in, for 8-12V on the light circuit, and the wiring/connectors leading to the information display PCB.