Where is the EZK Ignition Module specifically located? Do I remove the speedometer cluster or go under the dash the get it?
It's my last try on the previous high idle issue I've been having. I tried ALL the suggestions listed by the kind BrickBoard members and the problem persists.
I've even "jump wired" components bypassing the wiring harness and still come up with no OBD codes and the same 1600-1800 RPM idle issue after W.O.T. operation on the road.
I see on the wiring diagram the TPS runs through the EZK Module before going to the ECM.
B230FT runs excellent otherwise, but somehow the ECM is getting a signal to tell the ICV to bump up the idle.
Anyhow, if you could tell me what the EZK Module looks like and how to get to it, I'll pull it from a junker for about $25.

John

Remove the knee bolster over the drivers knees.
There are (3) Torx Screws on the front edge and (2) trim clips on the rear edge.
I't pretty easy to get off and to replace.

There is a guide pin on the bolster that slides into a hole in the dash, so you have to pull it straight out after removing the screws and trim clips.
That guide pin makes it a whole lot easier to re-install because it aligns all of the screw holes back up.

The Ignition Module is just to the right of the steering column inside the dash. (looking towards front of the car.).
It has a black plastic housing and the wiring harness plugs in from the bottom.

Hope this helps
steve

Most of the 1994+ turbo 940s have what is called the Gold EZK. It is gold in color, and it can be re-chipped for a more aggressive spark advance. See the image below.


--
john

Thanks John.
I see your postings frequently on this site and find you quite knowledgeable. Do you have any ideas on my high idle problems ONLY after W.O.T.? I shut the engine off and immediately restart and idle is normal.
OHM and voltage tests have been conducted on the TPS, EGR, ECT and ICV as well as all related wiring harnesses. I've rotated 3 known good ECM's into car
with same results.
What is telling the ECM to send a high idle message to the ICV? My friends and I are stumped and we've thrown every part and wiring check at it. No vacuum leaks anywhere. Tip-Top running B230FT except for this damn 1800 RPM idle after full throttle driving.
Any of your knowledge/experience would be greatly appreciated.
Thank you,
John

Hmm.... Doesn't the 94 940 turbo model have LH3.0+ bosch electronics? By + I mean "or a higher number".

I remember those having throttle position sensors that would adjust various things (like spark advance maybe?) based on throttle position. It might be worth a check.


The IAC or its spring could also be worn, damaged, or broken, and it could be sticking open because of the change in airflow going from WOT to closed throttle plate.

What I'm thinking is that on the transition from WOT back to a position where the IAC can have more influence on the idle, the IAC is being forced open and hanging.

Good Luck!

I've owned 7, 7/9's from 90 to 95, and they are all lh2.4. I believe the 3.0 was only on late 240's.

I'm at the end of ideas for this high idle problem. I even soldered the ground crimp connection, but terminal 5 on the ECM keeps sending a signal to the ICV to high idle. When the engine is turned off and immediately restarted, idle is normal. I have tried 3 different ECM's with same result. Same with the TPS and ICV.
The wiring harness has been completely OHM and voltage checked and the connectors are sound.
Something is sending a message to the ICV to open wide causing the high idle and the only thing that corrects it is to turn off car and restart.
Terminal 5 on ECM is a variable ground, but appears to be a hard ground causing the wide open ICV signal.
All the linkage is properly set and car runs great, except after full throttle operation, I can't bring it down from 1800 RPM unless I turn the engine off and start over.
Everything points to bad ICV or ECM, but can I have 4 bad ones each???
Tonight I changed the EX116 module also with no results.
What the heck am I missing?

My Volvo Service Manual for the LH Jetronic 2.4 shows that terminal #5 on the ECU to be solidly grounded....along with terminals 17, 19 and 29.

Out of curiosity, have you cleaned all of the ground points on the intake manifold?

steve

Looking back, I see that you've been having this problem for a while.
I haven't read all of the other posts, so maybe I can offer a new perspective.

The Idle Control Valve circuit and related components are wired like this....according to my schematics.

The Main Fuel Injection relay (terminal 87 blue/yellow wire) powers (+12V)terminal #1 on the Idle Air Valve, Terminal #5 of the Air Mass Meter, Terminal #1 of the "Air Pre-Heating PTC Resistor", and Terminal #9 of the ECU.
These points are "hot" whenever the Main Fuel Injection Relay is pulled in.
This Main relay is "pulled in" by a ground (-12V) signal from ECU terminal #21.



(Control) Grounding of components:

(1) Terminal #2 of the Air Pre-Heating PTC Resistor is solidly grounded at the right front engine compartment (black wire).
Whenever the Main Fuel Injection Relay pulls in, this resistor is energized.

(2) The Idle Air Valve is opened (or closed) by the presence of a Negative (-) 12V (grounding) signal to Terminal #2 on the Idle valve.
This ground signal (red/black wire) comes from the ECU terminal #33.

(3) Terminals 5 (brown wire), 17 (black wire), 19 (blue/black wire) and 21 (brown/black) wire) on the ECU are solidly grounded to the intake manifold, and should read 0 ohms resistance to the battery ground.

First, I would clean all of the engine ground points. The ECU controls components using negative (ground) signals.
A bad ground can cause a lot of weird things to happen.

If I had to make a guess why you have the idle problem that you have, I would guess that the idle valve is defective.

If not, then there is a "phantom" grounding signal getting onto the (red/black) wire from the ECU terminal #33 to the Idle Valve terminal #2.
A defect in the wiring insulation could cause this.

If this has not happened, I would try changing the Engine Temperature Sensor.

I'm not a expert on Turbo engines, so I'm giving you this information for reference only.

hope this helps
steve

Some excellent technical information! Thank you very much for taking the time to write a trouble shooting flow chart for me.
There are some items I have not checked.
I will today and report back.

Hello,

Try to disconnect the ICV electrical connection during high idle.

If the idle remains high then another scenario is possible (although remote). Your intake pressure could remain high after WOT leading to air forcing past the ICV. A blocked flame trap or oil trap (the black box) or loose vacuum hose connecting to the turbo wastegate could be possible. Turning off engine could lower down this pressure thus back to normal idle.

Hope this helps.

Amarin.

I replaced the black box and all "PCV" venting connections, but have not checked the turbo waste gate. Your excessive pressure makes theory sense. I'll check it today and report back. Thanks!

Hello,

Yes its a theory. I thought it could be a fault elsewhere after so long chasing the ICV line of troubleshooting and almost getting nowhere..

Also try to clean the insides of the vacuum nipples where all small vacuum hoses are attached to. It could be full of crud restricting vacuum flow. Simple tool such as a small needle or wire would suffice.

Hope this helps.


Amarin.

Hello,

According to 1994 Volvo wiring diagram book the 940 turbo is still using the EZ116K Ignition box with LH2.4 engine control unit. The TPS is connected for idle sensing only.

This means of the three wires coming from the TPS (orange, black and red-white) only the orange is connected to the ECU and ICU, while the black is connected to ground (on top of intake manifold no.3). The WOT wire (red-white) is not connected in turbo. In non-turbo 940 instead, the WOT wire from TPS is connected ultimately to pin no.3 on the LH2.4 ECU.

Hope this helps.

Amarin.

When you experience the high idle problem, try pinching the hose feeding the IAC (same as ICV) flat. This model of IAC is spring loaded to the closed position, and it takes voltage (from the ECU) to make it open. If the engine quits with the IAC pinched shut, you've verified the IAC is staying open. If the IAC is staying open, disconnect the electrical connector from it while you are experiencing the high idle problem. With no voltage from the ECU, the IAC has to go closed, and the idle to zero.

For your information, the ECT sensor is actually two units in one. One side is for the ECU, and the other side is for the EZK. The ECT for LH 2.4 is internally grounded. The ECT resistance figures are the same for the ECU and EZK. The ECT for LH 2.2 is externally grounded and is for the ECU only.

Let me know what you find.
--
john

Thanks again everyone. When the problem is solved I will certainly post the final cause.

John

"I see on the wiring diagram the TPS runs through the EZK Module before going to the ECM."

The TPS signal goes to both units at the same time (in parallel):

ECU pin 2 via connector C54
ICU pin 7 via connector C51

--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Hello,

According to the Volvo 1994 wiring diagram book TP3904202, the C54 connector is located within the engine compartment, front passenger side, behind strut tower near the firewall. The C51 connector is located within the engine compartment, driver side, behind strut tower, near the firewall.

In both connectors the wire from TPS is bright orange in colour. In 940 turbo version the WOT wire (coloured red-white) from TPS remains not connected at connector C54.

Try to clean all bullet connections within the connectors. They may be corroded.

Hope this helps.

Amarin.

Thanks Amarin, I think you're right. On second look it's the ECT sensor that goes to the EZ116K box.
I'm going to take your advise and clean all the connections and advise on the results.

John

Dear 94 945T,

Hope you're well. The ignition module is under the speedometer cluster. You do not need to remove the cluster. Remove the under-dash panel (above the driver's footwell).

In the space above the driver's footwell and under the dashboard you will see: (a) the ABS module, which is rectangular and has an aluminum case;
(b) the cruise control model, which is rectangular, has a brown plastic case with white letters/numerals, and is mounted against the left side of the under-dash area; and
(c) the ignition module, which - if memory serves - has a black plastic case, and is about four inches square. It should have a Bosch part number that starts 0 227 400 xxx. The last three digits likely are 207, but could be different.

Hope this helps.

Yours faithfully,

Spook