Alright I'm gonna need help from the Bosch ignition experts on this one. I'm at my absolute wit's end with this ****ing car and I'm seriously considering taking it to the junkyard. Please help me avoid having to do that.

Currently trying to chase down a no spark/no start issue on my 1989 (so it has Bosch LH2.4) 245. It was intermittent for a couple weeks but now it won't start at all.

The whole system looked pretty old so I replaced (in order):

-Crank position sensor (the one on top of the bellhousing)

-Cap/wires/plugs/rotor

-Coil

-Power stage (aka the ICM aka the ignition amplifier, it's the little thing behind the driver's side headlight)

None of that made any difference. Still no spark and no start. I removed the EZK box, took the computer out just to see if there was any obvious corrosion or blown components. The thing still looked brand new so I put it back in it's case.

Earlier today I put my meter on pin #5 of the plug that goes to the ICM up by the driver's headlight. This is the pin that should be receiving the AC signal from the EZK (which is receiving it from the crank position sensor) and got nothing. So I know it's either an issue with the brand new CPS, the EZK, or the wiring somewhere between the three components.

I tested the resistance of the CPS and got 170 ohms which is right within spec (150-230 ohms). Next I'd like to try and test to see if the sensor is putting out a signal while the engine is cranking, but I'm not sure how to do that. There are three pins on the connector and I don't know which ones I should be putting my probes on while the engine is cranking.

Can anyone offer any advice or explain to me how I can test the CPS? Any help is greatly appreciated.

EDIT: Wanted to add that all parts were OEM or equivalent and I also replaced the fuel pump relay as that was originally what I suspected was causing the intermittent no-start.

 

Any codes stored in OBD?

 

In for info. Same car.

 

Spark or fuel? First thing, spray some starting fluid in the intake while cranking to see if it fires up. Have you looked at the MAFS? Common failure item with mysterious symptoms.

 

I'm not getting any spark.

I'm not getting the correct pulse at pin #5 of the connector to the powerstage while cranking. This has nothing to do with the MAF.

 

Any codes stored in the Ignition or fuel control units? Code chart courtesy of https://www.volvoclub.org.uk/faq/EngineOBDCodes.html

Is the "shutter wheel" (sorry don't remember what it's called) on the flywheel/flexplate undamaged? I seen bolts get caught in the bell housing and damage the flywheel to the point the engine speed sensor does not send a usable signal. Note there's no codes related to the ignition amp - I always tested by substitution. (I remember some test in a green book - but swapping was faster)

If your injectors are firing then your speed sensor is working.

 

Using the on-board diagnostics, the EZK gives a 1-4-1 (or it could be 1-1-4, I don't remember) code for the CPS which means it likes what it's seeing from the CPS.

I don't believe that the injectors are firing while cranking. I used the on-board diagnostics to fire the injectors and I was seeing 1.5V AC across the terminals on my meter. While cranking, I only saw .3V. Also when I try to use the ECU's procedure for testing the CPS, it doesn't seem to do anything when I crank the engine for 5-10 seconds, indicating that the ECU may not be getting the proper signal from the EZK.

 

Do you mean to say it "does not like" what it's seeing from the CPS?

 

Nope. When I jumper pin 2 on the diagnostic box (the pin for ignition testing), press the button two times for 1-3 seconds each and observe the flashing LED, and then crank the engine over, it gives me code 1-4-1. Which means that the EZK is reporting that the CPS is working properly.

 

Got it. My shops or I never spent much time with diagnostic mode 2. How about when you simply check codes using mode 1 in both the ign and fuel systems? Usually if there are no codes we'd start looking at items that won't show codes. Connections, shredded wiring, ign amp, relays, etc. Then when a tech would say "Needs a control unit", I'd drive 15 minutes to my friends used Volvo parts warehouse, pick one up - tech would try it - then he would find the real problem.

 

It doesn't currently have any fault codes stored, but at this point I've replaced ALL of the components after the EZK that could be causing a no-spark (plugs, wires, cap, rotor, coil, and powerstage) with brand new OEM units. I know the coil is getting 12V on both terminals with the key on but the powerstage is not getting the pulsed signal on pin #5 while cranking. So clearly the CPS signal is getting to the EZK, but it's not putting that out to the powerstage. I tested all of the wires on the powerstage connector for continuity with the correct pins on the EZK connector, and all of them tested good. So I know it's not a broken wire there.

Another thing that makes me suspect the EZK is that when I try to use the ECU diagnostics for the crank position sensor, it doesn't seem to work. I do the whole process to get into the ECU diagnostics and get the flashing light on the black box, but then when I crank the engine over to generate a signal from the crankshaft position sensor, nothing happens. But I'm not sure if simply cranking it is good enough to generate enough of a signal for the ECU to pick up on, or if the engine has to be fully running (which obviously I cannot do at the moment).

But my point is that both the ECU and the powerstage are SUPPOSED to get the pulsed CPS signal from the EZK, and it SEEMS as though neither one is getting it at the moment as far as I can tell.

 

Update for today:

I used my test light and I'm not getting any pulse at the coil or at the #5 grey wire of the powerstage connector.

I got 170 ohms between pins 10 and 23 on the EZK connector so I'm fairly certain my brand new Bougicord CPS is good. The on-board EZK diagnostics still give me code 1-4-1 for it as well.

I tested all of the terminals on the powerstage connector for continuity with wherever they're supposed to go, and all tested good (except for that one black 'shiedling' wire which doesn't really 'go' anywhere).

I actually replaced the EZK today with a known good unit that just came out of a running car and did all the diagnostics above AGAIN and no change.

At this point I'm really at a loss. I seriously just want this thing to run so I can sell it and get it out of my sight. The car is going to the junkyard in the next week if I can't get it running.

 

just to be clear there is no spark at all coming out of the new coil/ new coil wire?

 

Absolutely no spark nor any signs of it.

 

Since the CPS provides the signal to the EZK I would start there. The CPS works in conjunction with the "tone ring" that is on the flywheel/flex plate. The tone ring has notches cut out at regular intervals with the exception of on spot that doesn't have the notch. As the tone ring spins the notches cause pulses to be generated in the CPS which are read by the EZK. Since your not getting pulses you may want to check that the tone ring is intact and not bent/broke. There is a plate at the bottom of the bell housing that can be removed to allow access to the flex plate bolts. Remove the plate and inspect the tone ring for damage.

 

Update for today:

I took the EZK out of its box and plugged it in. Tested pins 5 & 6 for voltage both with they key on and while cranking; both had 12V under all circumstances. Also tested pin 20, which did not have 12V under any circumstances. So everything checks out there.

How can I test for the CPS signal at the pins in the EZK? I know it comes in to pins 10 & 23 but I'm not sure how to test it. I ordered a scope that should be here tomorrow or Friday so I can use that to try and diagnose this further.

At this point I'm convinced it has to be something with the CPS signal (even though it's a brand new unit, the on-board diagnostics indicate that it's fine, and passes the resistance test at the EZK connector). If I have time tomorrow I'm going to take the bellhousing cover off to check out the condition of the tone ring. In the meantime, I'm willing to try pretty much anything, so please chime in with any suggestions.

 

That is certainly a possibility as a couple of us have mentioned that.

 

The reason I didn't think it was the culprit (and still don't) is because it always passes the EZK's diagnostic test. So clearly the EZK is happy with the signal that it's getting from the CPS. But I'm really running out of stuff to even test here so I guess it's worth a shot.

 

If you pull a spark plug out is it wet or dry. As you would expect if wet then no spark and if dry then no injector pulse. Also if you put an inductive pickup on the coil wire do you see it light.

 

The injectors are not firing while cranking. I tested across one of the plugs with both a DMM and test light and got nothing. And I was still able to fire them using the ECU's diagnostics so I know that they're good.

So clearly the EZK is not putting out the proper signal to either the powerstage or the ECU.