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All,
Compliments of chasing an intermittent no-start for months (only lasted a minute or 2 then started right up) I have new (not used): FP Relay, CPS, power stage, coil, and some spotless grounds. It had been running for several weeks with no problem after the last component replacement (power stage) so I had my finger crossed that it was solved. Now the intermittent came to stay and it won't start permanent. Lucky for me it happened right in front of the house.
I have +12 both sides coil with key on but no spark in the coil wire during crank as verified by timing light and my nifty spark gauge I built around plug wire 1 which lights a neon light on the dash. I ran out of light today but according to the very good 740/940 no start guide I need to verify the inputs to the power stage next. I can't believe the 3 week old power stage is bad so let's say I verify the inputs and they are not good. What does that tell me? The no start guide kind of ends there. All I can think of is the ECU not providing signal to power stage or the ignition switch is not providing voltage. Am I missing something else?
Thanks,
Robb
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My 1993 245 was fixed last year after many hours of measuring voltages by replacing my Ignition Module (about $80). I suggest buying a spare and swapping it in if you suspect it. It's cheap and easily put in (even with spreading the thermal paste). I even keep a spare AMM just in case.
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This thread has been a shameful waste of space here on the brickboard as my no spark problem turned out to be one of the most basic types and I have to hang my head in shame here. When Art suggested pinging the ODB just to see if I get the 1-1-1 code as verification the ECU was powered up I discovered I was getting no codes at all - just no response for either the pin 6 or pin 2 codes. So back to basics I turned the key on and started verifying voltage on the downstream side of the fuses. When I got to fuse 6 when I pushed the DVM probe onto the fuse holder to make contact I suddenly heard the fuel pump power up. I cleaned it up and verified I get codes from obd and it starts right up. So the problem was bad contact at fuse 6 which apparently powers the ECU too. This just re-enforces the cleaning of the fuses as preventive maintenance. I know it was no more than 6 months ago that I cleaned and applied dielectric grease and already some of the 16 ampers had white corrosion on them. They really are an achilles heal on these cars. Thanks to all and especially Art for the valuable input.
Robb
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I was going to suggest rolling the fuse but figured you already covered that! Lesson for all, check fuses and roll for corrosion.
Come to think of it I fixed my daughters car a few months ago when she was having a starting problem.
The only thing I really did was roll the fuses, at the time I was not very confident I had done anything to solve the problem. But I have not had a call back on it.
Dan
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I just bought $18 worth of 8 and 16 amp fuses to completely replace those in three cars I don't see often. They are the brass element fuses, so I hope to eliminate the dissimilar metal corrosion that seems to occur with the tin alloy types. I think they are the same ones carried by eeuroparts; I got mine from FCPG.
This is the time of year for fuse rolling. One of the cars got its window stuck down for the need to roll fuse #12.
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Art Benstein near Baltimore
"Most people work hard enough not to get fired and get paid just enough not to quit."
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Intermittent problems are a real PITA to correct.
If there is no pulse voltage to the - terminal of the coil, then it's possible you have a bad ignition computer. Is it a Volvo one or aftermarket? My car had a Programma brand ICU installed by the PO. I had intermittent ignition failure that I couldn't figure out. I talked to a Volvo mechanic and he told me that he'd had nothing but trouble with that brand. I got a used Volvo unit and haven't had the problem since.
Charlie
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1985 244DL B230 M46 170k
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Charlie, I read about yours before. That's a strange story, because yours, if the one in your sig, is a Volvo/Chrysler ignition system. They've had trouble, yes, especially with the harness connector, but on the whole they are reliable enough to make them plentiful and cheap on the used market, so I have no idea why Programa would do anything but test and resell them.
Robb's car, a '93, has the Bosch system, EZ116K, used since 1989 along with LH2.4 and LH3.1 fuel systems. Here are the components, crank sensor, ECU, and power stage. I've been hanging around here for 11 years and have yet to hear of an EZK ICU needing replacement. Hope this isn't the first.
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Art Benstein near Baltimore
The math professor went crazy with the blackboard; he did a number on it.
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Yes, I'm talking about my '85. I eliminated every other ignition component and finally decided to check out the ICU. I took it to a Volvo mechanic and he immediately said "That box is your problem." He said that he'd had nothing but problems with them and sold me a used Volvo unit for $100. I plugged it in and haven't had a problem since.
I only suggested the ICU if there was an aftermarket one in. I'm pretty sure Programma makes ICUs, not reconditions used ones, as it looked much different from a Volvo unit. New Volvo units list for like $400 or something like that, so I wasn't about to spend that on a $200 car.
Other than my '89 which I owned for only a year before wrecking it at age 17, all my experience is with '85 and older 240s. I am out of my element on this thread, apparently, and retract my diagnosis.
Sorry for the bad advice.
Charlie
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1985 244DL B230 M46 170k
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Charlie,
I'd love to see a picture of that Programa ICU that was put in your 85. As to the "bad advice", come on, we're all just trying to be helpful. You have to own a lot of these cars before you figure out which years what changes got made. It could have been an ICU. Just because I haven't heard of it, certainly one EZK has failed somewhere, even if only done in by a leaky windshield.
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Art Benstein near Baltimore
Why is it that people say they 'slept like a baby' when babies wake up every two hours?
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Hi Robb,
Well, your neon light nailed the no-spark. Before that, we couldn't be sure it was ignition.
With a good CPS and power stage, most remaining ignition problems are poor connections. The power stage connector is in a lousy environment, and the harness connector at the coil has caused others trouble.
Ignition switch power is verified by your coil reading +12 at coil terminal 15. The ICU (never heard of one actually going bad) can be verified to be powered up by getting the 111 code from OBD pin 6. Actually the fact the OBD light works at all is testament to the ignition switch power being there.
Testing for signal input to the power stage is an iffy thing. The book will give you a voltage to expect, but every DVM is different about the way it reports a pulsed waveform. An LED test light at the power stage input would blink while cranking, and any DVM reading above 0.5 volt would satisfy me there's a signal there.
Here's what you're up against. The bottom trace in the photo below shows the input to the power stage, same as output of the EZK, going to +5V for 1/6th of the time - averaging something less than a volt. Without a scope, you depend on how your DVM responds to this (sample time, averaging) which isn't the same for all meters.
I haven't had to yet, but here's how I think I would approach your trouble. I'd pull the boot from the power stage connector so I could back probe each terminal, and using a test light, verify power on 4, no power on 2 or 3, and look for winking power on 1 while cranking. I'd use an LED test light to view the signal on pin 5.
This is an LED test light.
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Art Benstein near Baltimore
Birds are grouchy in the morning because their bills are over dew.
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Art,
put everything back together and decided to start with the obd code check and I'm getting nothing. I tried the lead in slot 6 and pressed once - nothing. Onc section in Bentley says press twice so I tried that - no codes. Then I tried wiht the lead in slot 2 (fuel system checks) and again it gives no codes. Now I'm going out (when I dry out) to get to the ECU and verify power at pin 6 and ground at pin 20 and 14. Boxvolvo suggested the tach might be shorting out - I was all hot on that but now just seems the ECU is not on. Sounds like the old 25 amp fuse but 91 and on don't have that. All fuses are good and hot with key on so power is going out to ECU I suppose. Any other ideas apprecieated.
Robb
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Thanks Art - as always a chocked full of info reply. Let me get a clarification if I can - the power at pin 4 on the power stage is just with the key on, not cranking right, ie, the only test while cranking is at pin 1 where you want to see a winking led test lamp, right? I'm not exactly sure where I'm going yet but I'll get on this in the morning. If the ODB says ECU is powered up and the inputs are all there at the power stage but there is no spark then I'm looking at a dead 3 week old Volvo OEM power stage? That doesn't seem likely. I guess it could be wiring from power stage to coil. I did try the test where you measure the ac voltage at the red/white wire on the coil coming from the stage while cranking and really didn't see any although as you say DVM's are spotty in these areas. I'll see tomorrow and post back. I'm sure glad this stopped being intermittent and right in front of the house too!
Thanks again,
Robb
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Try the unusual.
Do you have a tach? If so, try removing the tach pickup wire from the coil.
A shorting tach pickup wire will provide a path to ground for the minus side of the coil, and prevent the break in the ground necessary for the coil to discharge.
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Boxvolvo - this could be the clue I've been looking for. This exact thing happened on our boat last year. Pulled the tach wire off and it started right up. (STill haven't replaced that tach yet) The Bentleys diagram is obscured around the coil by the grid lines - there are 2 red-white wires coming off coil, one to FP relay and one to tach. There's something else written next to R-W but you can't read it. I wonder how I can tell which one is which??
Robb
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Only sure way is to trace the two R-W wires off the coil. You could try removing them from the coil one at a time, see what happens.
Mind you, this is a longshot, but I've had it happen two times in forty years.
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Let me get a clarification if I can - the power at pin 4 on the power stage is just with the key on, not cranking right,
Well, yes actually, it needs to be there both key on and key in crank position. The only thing that would keep it from being there while cranking yet be there with key on, I think, would be an ignition switch failure. Very possible, but not likely to marry up to your stall when running symptom from before.
I guess it could be wiring from power stage to coil.
Yes, and don't forget that includes the pins that make contact to the power stage. I too, highly doubt you've fried a new power stage, but you have your old one, so if it comes down to that, swap them. Electrical parts fail near beginning and end of their expected lifecycle.
There's lots of hand-wringing on this site about the heat sink transfer grease, but worse for heat transfer would be a speck of dirt keeping the module from being flat against the heat sink, whether or not the grease was properly used. This isn't the weather those failures occur in. As long as your coil is the correct part and not shorted out inside, the power stage should last another 20 years.
The AC range should help, but I would think you'd want to be familiar with your meter's response to coil term. #1 during cranking on a good, working example before you interpret the reading. Again, here, a test light is a better tool.
Tomorrow, working outside won't be any fun at all.
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Art Benstein near Baltimore
Thieves who steal corn from a garden could be charged with stalking.
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