v70xc - 00 200hp - intermittent refusal to start

[blompa]

Hello there,

firstly thanks for the wealth of information I've found here.

On to my problem:

Me and a buddy are fiddling with an v70xc that refuses to start. We cannot connect to the ECU for code reading. (we lack one of those Volvo hardware interfaces. I was under the impression that a super old school code reader would work just as well but no luck).

Here's what we know for sure:

• every time it refuses to start it gives us IMM-321
  Car always turns over but has no spark and no fuel during refusals (which confuses me since immobilizer problems have been seen to be no crank. But I haven't been able to tell for sure if that applies to this model. I assume it does not)
  Crankshaft sensor has been measured and works. Nice sine wave.
  ECU has been disassembled. Nothing burnt, no visibly broken solders.
  We've tested all fuses and none of them seem broken.
  Fuel pump primes correctly every time.
  Battery is good and recently charged
  Car has been in a warm garage for 2 weeks now
  When we disconnect the antenna ring around the ignition key we received another error code in addition to the IMM-321
  Fuel pump relay works could of course be intermittently working)
  We measured the +12v connectors on the box and they all had power accordingly

Our theories have been raging from broken immobilizer through fuel pump relay to bad grounding on the ECU to bad cabling or some kind of short circuit.

Here's what we discovered last night:

1: attempt to start => fail
2: turn key to 0.
3: disconnect battery.
4: Turn key to 3. stay here for 5-10 seconds
5: turn key to 0
6: reconnect battery.
7: start car
8: engine running (for enough minutes to tell us it is not a fluke)
9: key to 0.
10: key to 3 => no start

(
Not sure if it works if we remove the key between 5 and 6. This can be tested if it helps out with the diagnosis.
9 and 10 are consistent regardless of whether we remove the key or not.
IMM-321 shows up around 9 or 10. It should not be there during 8 but I cannot verify that right now.
)

We attempted this since I believed that the car started if the charge was allowed to dissipate from all capacitors. Step 4 replaces time(where time > ~20minutes) by forcing a discharge.

What should this tell me?
Any ideas or leads?

On the plus side. The car is a bit more difficult to steal (unless they tow it )

[jose456891]

Fix whatever is preventing you to read the codes. Otherwise there is not much to work with. I would start by downloading wiring diagrams for your car and then tracing all related to ECU power and OBD2 communication. Check for a faulty ignition switch, relays, fusible links, and fuses.

Something tells me that you are experiencing multiple issues, the most obvious being electrical.

A little googleing resulted in the following: https://www.matthewsvolvosite.com/forums ... =1&t=48752

Also try to bypass the immobilizer

[jblackburn]

Though it shows a different code for the antenna ring being unplugged...I would start there. The antenna ring not reading a signal from the key and disabling the car is a known issue, usually where the contacts to the antenna ring get dirty.

[xrayspex78]

jblackburn has a great solution. I second the antenna key ring as well. I had a 2000 S-70 that would start then stall. Turned out to be the antenna key ring. Different symptom but it did fail.

[blompa]

Thanks for the replies.

@jose456891
That guy seems to have the "starts and runs for a second" - problem.
Which is different from what we're experiencing.

Also try to bypass the immobilizer

I've thought about this. For older cars you're shorting out some connector between relay 210 and 211. Those slots are not populated for the 2000 model. Any leads for how it is done on a year 2000 version?

@jblackburn/xrayspex78
Are you saying that on the 2000 model the engine will be allowed to turn over (via the starter) but not ignite or give fuel if the immobilizer is activated / no signal from they key?
I've been having problems verifying the exact behavior of the engine when the car is immobilized.

_____________________

The thing is. The car runs fine. For the first start attempt. It runs until we turn it off.

If we try to start it again it will turn over on the starter but not ignite.

The antenna ring connector has been sprayed with contact spray.
It can of course still be broken. But this does not explain why the car starts right after having had the battery disconnected for a short time?

[E Showell]

If you have not traced the battery cables all the way along their respective travel paths, please do so. I have a positive cable corroded almost completely through near the end connection to the starter. Without getting down there right up next to it, you couldn't even tell it was a problem. Wiggle the wires, get under the car and check its run along the front crossmember. I would counsel against cutting off the end fitting and screw clamping a new end fitting on -- that's a short-term bandaid at best.

[blompa]

OK,

We've done some more debugging.

Antenna
Firstly, we tested with another antenna. Same behavior. Removing the battery resets something and the car starts(it will suffice to just remove the ECU for a while but battery is way simpler).


We've also managed to connect to the ECU. It has no fault codes at all. (Software used is both Digimoto 3.7 and Torque on an android cell phone). Torque did a full diagnostics of the box and came back blank.

The ECU is only connectible during or before the first start-up.

After the engine is turned off again, the ECU is dead as a door knob(won't answer from our OBD software). We made sure it was not the immobilizer messing with us by bypassing it during OBD connection (OBD-wire (7th from the left on the wider row) on the connector between the seats goes to a white wire, #3 on the immobilizer connector. #4 on the same connector goes to the ECU).

Something tells the ECU to do some kind of lockup as we turn the engine off. It could be the Immobilizer box. Not sure.

We might need some kind of better software, Vada/Vadis with h/w interface. Or similar.

@E Showell
Are you saying that a frayed connection to the starter could cause the problem somehow? The starter always turns over. Always. But the ECU does not seem to work or is forcefully disabled during a second start attempt.

[Antsu]

Hello..
I Have same kind problem on my 1999 V70 2,5T AWD ... Did you find the reason on this problem?... Mine give troublecode IMM- 233 by Vida... When i start first time ...its running great... When i try it again... "engine light" dont lit... and it s crank but no run.
Then ..if i cut off the battery cable few seconds .. Now try again.. "engine light" come on and its start and running fine..

This is very mystery problem... The key ring by IMM looks fine...

?????????????????????????