1996 Volvo 850 turbo, cel coming on after running 5 sec

Bowtiekilla02 · Post by **Bowtiekilla02** » 21 Jul 2015, 17:56

So my wife and I hit a deer in my 850 this past week and I bought a parts car to fix it. It had damage to the hood and didn't hit the bumper or mess up the fenders at all. It broke the radiator and the intercooler and a/c condenser. Before my car had no check engine lights drove fine etc. Once we stripped the parts off the parts car that also ran with no cel. The car would not start. the up arrow was flashing and the fuel pump would only stay on for a brief second. Found poor connections at the fuel relay above the radiator, plus wiggled the wire connector at the IAC and the car started up and ran but the check engine light was on. The code was p0120 for a throttle position sensor. But the code will not come on until you run the car for 5 seconds. If you cut the car off and re start it the cel will be off and reappear after 5 seconds. We changed out the throttle position sensor from the parts car to the other one, still same thing. Reset the ECU by holding the positive and negative together still same thing, changed out the ECU still same thing. The only electrical parts that was touched in the change out was the relay fan sensor the connections to the fan itself the fuel relay, headlights, horns, air temp sensor, hood latch. There was no prior problem until we changed the parts out. Does anyone have a clue what it could be? When I connect my computer to the car it doesn't recognize any codes, but the cel comes on after it runs for 5 seconds. The only code that came up when the arrow was flashing and cel was the p0120 code. My up arrow does not flash anymore, it only occurred when the car would not start.

Post by **Ozark Lee** » 21 Jul 2015, 19:58

Other than the CEL does the car seem to run and drive OK?

...Lee

Bowtiekilla02 · Post by **Bowtiekilla02** » 21 Jul 2015, 22:33

As far as I know yes. Haven't drove the car on the road yet due to waiting on the clamps and o rings for the oil and trans cooler lines.

Post by **Ozark Lee** » 22 Jul 2015, 07:32

Since you replace the throttle position sensor with a "know good" that pretty much leaves a wiring issue in the loom between the sensor and the ECU. Collision damage tends to be pretty indiscriminate and I think that loom runs down along the front of the subframe rail behind the radiator which is in the general area where the you had to replace things.

There are three wires that go to the throttle position sensor. A Brown/Black wire which is reference voltage and it is shared with several other sensors. A problem with that wire would likely cause the car to not run.

The other wires are an Orange/White wire and a Yellow wire and they go to the ECU at pins A16 and A15 respectively. I would use an ohmmeter to check those wires between the connector and the ECU pins locking for an open circuit, a short between the two wires, and a short to ground on either of them.

If you do find that one or both of the wires is bad it them becomes a matter of finding the spot where they got smashed and making the repair. making the repair is fairly easy but finding the bad spot can be tough.

...Lee

Bowtiekilla02 · Post by **Bowtiekilla02** » 22 Jul 2015, 07:45

Well the impact was it the top part of the front end, it only got my hood and radiator and a/c condenser and radiator suport, but didn't get my intercooler it survived. So the no wires anywhere was smashed during the hit. I'm having a guy tell me on volvo speed that if you get the tps code it also will store it in the tcm because it relies on the tps for shift points and other things and that any regular ob2 scanner will not read tcm codes. Any truth to that? Seems possible

Post by **Ozark Lee** » 22 Jul 2015, 08:18

Both the ECU and the TCU use the throttle position sensor to make decisions and an error code will indeed be stored in both modules.

...Lee

Bowtiekilla02 · Post by **Bowtiekilla02** » 24 Jul 2015, 21:37

Thank you I had it cleared today! Thanks for the good information!