1996 850R : No check engine light (Emissions light)

kevinwalter · Post by **kevinwalter** » 15 Aug 2015, 06:50

Hi,

I've just bought an 850R with a big problem. The car does not start. It cranks but it does not turn on.

I've checked every relay in the ECM and above the fan. Also all the fuses are looking fine. When I turn on the car, the "check engine" (My car has the emissions light) light does not light up. When I turn on the car without a ECU it's giving me the same lights. (I've disconnected the battery before removing the ECU)

These lights only light up:

The ECU is getting the right voltage. The mass looks fine to. When I measure the voltage at the camshaft sensor it is only 2 volts from the 12 volts it needs.

When I try to read the ECU through the OBD connector it can't connect to the ECU. It can connect to the automatic transmission module. (TCM) I'm trying this with the Volvo System Tester which has the ability to read the Motronic 4.3.

Does anyone has some more ideas?

I've seen a-lot of topics which ended without a solution.

Kind Regards,

Kevin

Post by **tryingbe** » 15 Aug 2015, 06:54

Have you check for fuel?
Have you check the compressor numbers?
Have you check for spark?
What kind of history did the last owner give you?

kevinwalter · Post by **kevinwalter** » 15 Aug 2015, 07:37

Have you check for fuel?
Enough Fuel, also pressure.
Have you check the compressor numbers?
Which compressor?

Have you check for spark?
Yes, no spark.
What kind of history did the last owner give you?
Nothing, thats why I bought this car cheap.

Post by **erikv11** » 15 Aug 2015, 08:17

He means compression: do the cylinders have compression.

No spark is a problem. This is usually due to a broken cam position sensor or a crank sensor.

The bulb is probably just burnt out, hence no check engine light.

kevinwalter · Post by **kevinwalter** » 15 Aug 2015, 08:36

He means compression: do the cylinders have compression.
I think the first thing to do is getting the spark work. If it's not running right I can do a compression test.

No spark is a problem. This is usually due to a broken cam position sensor or a crank sensor.
I've changed both with working ones. Did not work either. The CPS is only getting 2 of the 12 volts from the ECU. It needs 12 when I check it out,it only gets 2 volts.

The bulb is probably just burnt out, hence no check engine light.
I will try that by swapping it with one of the working ones. Every light is working so it's a bit weird that exactly that bulb has burnt out.

I've got an ECU from a 850 T5 AUTH. Can I swap it? Just to test.

Post by **erikv11** » 15 Aug 2015, 10:53

Also about the bulb, it is not uncommon for a seller to remove the CEL bulb to hide problems with the car. Maybe there isn't a bulb at all.

These comments are all for years in the US market:

A 96 R has a Motronic 4.3 (m4.3) ECU. I don't know what a "850 T5 AUTH" is but you can freely swap around m4.3 ECUs without any consequence, with the exception that the emissions equipment on the acceptor car may not match that of the donor, so you can get emissions ECUs.

You can also swap in a m4.4 ECU from a 98 but only if you make adjustments for air conditioning. You can do this by tuning the ECU or by making some hardware adjustments. If you don't, I think the consequence is you will fry the climate control head unit the first time you turn on the AC.

Post by **erikv11** » 15 Aug 2015, 10:55

Oh and on the no spark issue, apologies the first time I did not see that info in the bottom of your first post. How is the coil, do you have one you can swap? And the coil wire (maybe check resistance on it)?

kevinwalter · Post by **kevinwalter** » 15 Aug 2015, 12:46

Hi Erik,

I bought this car really cheap. I knew it was not running. When I check the voltage of the coil it's getting 12 volts. Looking good.

When I check the resistance of the coil:

Large nut: 8,22 kΩ (From the large nut to the center of the coil)
small nut: 8,22 kΩ (From the small nut to the center of the coil)
both = 0 Ω (From the large nut to the small nut)

Looks good to?

When I connect the special Volvo System Tester it cannot read the ME4.3. Only the TCM.
The TCM gave me an messages that there was something wrong with the TPS.

With 850 T5 AUTH i mean 850 T5 Automatic ECU. It looks like that every T5 used the me4.3.

Edit: Found someone with the exact same problem. The only difference is that I won't get a check engine light.(Which is maybe blown.) The voltages he's describing are exactly the same.

https://www.matthewsvolvosite.com/forums ... 0&start=14

kevinwalter · Post by **kevinwalter** » 18 Aug 2015, 09:36

Thanks to ProStreetDriver from the topic I mentioned above, it is working again! (even the check engine light) It was indeed the black/orange cable above the radiator(to the grey relay) that was broken on several places. After we've fixed that it fired right up! AFTER 1 year of sitting... Volvo POWER!!

Post by **erikv11** » 18 Aug 2015, 12:26

443k, impressive!

Nice work figuring that out. So a broken wire to the main fuel injection relay, results in a no spark condition?

This would be great info to remember, if you can confirm it. Not intuitive (but probably makes sense if we look at the wiring diagrams).

Can you post a pic of the wire that was broken?